diff --git a/spec/MockBlob.ts b/spec/MockBlob.ts
new file mode 100644
index 000000000..04d01c24e
--- /dev/null
+++ b/spec/MockBlob.ts
@@ -0,0 +1,27 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+export class MockBlob {
+    private contents: number[] = [];
+
+    public constructor(private parts: ArrayLike<number>[]) {
+        parts.forEach(p => Array.from(p).forEach(e => this.contents.push(e)));
+    }
+
+    public get size(): number {
+        return this.contents.length;
+    }
+}
diff --git a/spec/unit/models/MSC3089Branch.spec.ts b/spec/unit/models/MSC3089Branch.spec.ts
new file mode 100644
index 000000000..05c46653e
--- /dev/null
+++ b/spec/unit/models/MSC3089Branch.spec.ts
@@ -0,0 +1,153 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import { MatrixClient } from "../../../src";
+import { Room } from "../../../src/models/room";
+import { MatrixEvent } from "../../../src/models/event";
+import { UNSTABLE_MSC3089_BRANCH } from "../../../src/@types/event";
+import { EventTimelineSet } from "../../../src/models/event-timeline-set";
+import { EventTimeline } from "../../../src/models/event-timeline";
+import { MSC3089Branch } from "../../../src/models/MSC3089Branch";
+
+describe("MSC3089Branch", () => {
+    let client: MatrixClient;
+    // @ts-ignore - TS doesn't know that this is a type
+    let indexEvent: MatrixEvent;
+    let branch: MSC3089Branch;
+
+    const branchRoomId = "!room:example.org";
+    const fileEventId = "$file";
+
+    const staticTimelineSets = {} as EventTimelineSet;
+    const staticRoom = {
+        getUnfilteredTimelineSet: () => staticTimelineSets,
+    } as any as Room; // partial
+
+    beforeEach(() => {
+        // TODO: Use utility functions to create test rooms and clients
+        client = <MatrixClient>{
+            getRoom: (roomId: string) => {
+                if (roomId === branchRoomId) {
+                    return staticRoom;
+                } else {
+                    throw new Error("Unexpected fetch for unknown room");
+                }
+            },
+        };
+        indexEvent = {
+            getRoomId: () => branchRoomId,
+            getStateKey: () => fileEventId,
+        };
+        branch = new MSC3089Branch(client, indexEvent);
+    });
+
+    it('should know the file event ID', () => {
+        expect(branch.id).toEqual(fileEventId);
+    });
+
+    it('should know if the file is active or not', () => {
+        indexEvent.getContent = () => ({});
+        expect(branch.isActive).toBe(false);
+        indexEvent.getContent = () => ({ active: false });
+        expect(branch.isActive).toBe(false);
+        indexEvent.getContent = () => ({ active: true });
+        expect(branch.isActive).toBe(true);
+        indexEvent.getContent = () => ({ active: "true" }); // invalid boolean, inactive
+        expect(branch.isActive).toBe(false);
+    });
+
+    it('should be able to delete the file', async () => {
+        const stateFn = jest.fn().mockImplementation((roomId: string, eventType: string, content: any, stateKey: string) => {
+            expect(roomId).toEqual(branchRoomId);
+            expect(eventType).toEqual(UNSTABLE_MSC3089_BRANCH.unstable); // test that we're definitely using the unstable value
+            expect(content).toMatchObject({});
+            expect(content['active']).toBeUndefined();
+            expect(stateKey).toEqual(fileEventId);
+
+            return Promise.resolve(); // return value not used
+        });
+        client.sendStateEvent = stateFn;
+
+        const redactFn = jest.fn().mockImplementation((roomId: string, eventId: string) => {
+            expect(roomId).toEqual(branchRoomId);
+            expect(eventId).toEqual(fileEventId);
+
+            return Promise.resolve(); // return value not used
+        });
+        client.redactEvent = redactFn;
+
+        await branch.delete();
+
+        expect(stateFn).toHaveBeenCalledTimes(1);
+        expect(redactFn).toHaveBeenCalledTimes(1);
+    });
+
+    it('should know its name', async () => {
+        const name = "My File.txt";
+        indexEvent.getContent = () => ({ active: true, name: name });
+
+        const res = branch.getName();
+
+        expect(res).toEqual(name);
+    });
+
+    it('should be able to change its name', async () => {
+        const name = "My File.txt";
+        indexEvent.getContent = () => ({ active: true, retained: true });
+        const stateFn = jest.fn().mockImplementation((roomId: string, eventType: string, content: any, stateKey: string) => {
+            expect(roomId).toEqual(branchRoomId);
+            expect(eventType).toEqual(UNSTABLE_MSC3089_BRANCH.unstable); // test that we're definitely using the unstable value
+            expect(content).toMatchObject({
+                retained: true, // canary for copying state
+                active: true,
+                name: name,
+            });
+            expect(stateKey).toEqual(fileEventId);
+
+            return Promise.resolve(); // return value not used
+        });
+        client.sendStateEvent = stateFn;
+
+        await branch.setName(name);
+
+        expect(stateFn).toHaveBeenCalledTimes(1);
+    });
+
+    it('should be able to return event information', async () => {
+        const mxcLatter = "example.org/file";
+        const fileContent = {isFile: "not quite", url: "mxc://" + mxcLatter};
+        const eventsArr = [
+            {getId: () => "$not-file", getContent: () => ({})},
+            {getId: () => fileEventId, getContent: () => ({file: fileContent})},
+        ];
+        client.getEventTimeline = () => Promise.resolve({
+            getEvents: () => eventsArr,
+        }) as any as Promise<EventTimeline>; // partial
+        client.mxcUrlToHttp = (mxc: string) => {
+            expect(mxc).toEqual("mxc://" + mxcLatter);
+            return `https://example.org/_matrix/media/v1/download/${mxcLatter}`;
+        };
+        client.decryptEventIfNeeded = () => Promise.resolve();
+
+        const res = await branch.getFileInfo();
+        expect(res).toBeDefined();
+        expect(res).toMatchObject({
+            info: fileContent,
+            // Escape regex from MDN guides: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions
+            httpUrl: expect.stringMatching(`.+${mxcLatter.replace(/[.*+?^${}()|[\]\\]/g, '\\$&')}$`),
+        });
+    });
+});
diff --git a/spec/unit/models/MSC3089TreeSpace.spec.ts b/spec/unit/models/MSC3089TreeSpace.spec.ts
index ea6078a67..3aebe5af1 100644
--- a/spec/unit/models/MSC3089TreeSpace.spec.ts
+++ b/spec/unit/models/MSC3089TreeSpace.spec.ts
@@ -17,13 +17,14 @@ limitations under the License.
 import { MatrixClient } from "../../../src";
 import { Room } from "../../../src/models/room";
 import { MatrixEvent } from "../../../src/models/event";
-import { EventType } from "../../../src/@types/event";
+import { EventType, MsgType, UNSTABLE_MSC3089_BRANCH, UNSTABLE_MSC3089_LEAF } from "../../../src/@types/event";
 import {
     DEFAULT_TREE_POWER_LEVELS_TEMPLATE,
     MSC3089TreeSpace,
     TreePermissions
 } from "../../../src/models/MSC3089TreeSpace";
 import { DEFAULT_ALPHABET } from "../../../src/utils";
+import { MockBlob } from "../../MockBlob";
 
 describe("MSC3089TreeSpace", () => {
     let client: MatrixClient;
@@ -37,8 +38,8 @@ describe("MSC3089TreeSpace", () => {
     beforeEach(() => {
         // TODO: Use utility functions to create test rooms and clients
         client = <MatrixClient>{
-            getRoom: (roomId: string) => {
-                if (roomId === roomId) {
+            getRoom: (fetchRoomId: string) => {
+                if (fetchRoomId === roomId) {
                     return room;
                 } else {
                     throw new Error("Unexpected fetch for unknown room");
@@ -735,4 +736,112 @@ describe("MSC3089TreeSpace", () => {
             expectOrder(d, 3);
         });
     });
+
+    it('should upload files', async () => {
+        const mxc = "mxc://example.org/file";
+        const fileInfo = {
+            mimetype: "text/plain",
+            // other fields as required by encryption, but ignored here
+        };
+        const fileEventId = "$file";
+        const fileName = "My File.txt";
+        const fileContents = "This is a test file";
+
+        // Mock out Blob for the test environment
+        (<any>global).Blob = MockBlob;
+
+        const uploadFn = jest.fn().mockImplementation((contents: Blob, opts: any) => {
+            expect(contents).toBeInstanceOf(Blob);
+            expect(contents.size).toEqual(fileContents.length);
+            expect(opts).toMatchObject({
+                includeFilename: false,
+                onlyContentUri: true, // because the tests rely on this - we shouldn't really be testing  for this.
+            });
+            return Promise.resolve(mxc);
+        });
+        client.uploadContent = uploadFn;
+
+        const sendMsgFn = jest.fn().mockImplementation((roomId: string, contents: any) => {
+            expect(roomId).toEqual(tree.roomId);
+            expect(contents).toMatchObject({
+                msgtype: MsgType.File,
+                body: fileName,
+                url: mxc,
+                file: fileInfo,
+                [UNSTABLE_MSC3089_LEAF.unstable]: {}, // test to ensure we're definitely using unstable
+            });
+
+            return Promise.resolve({event_id: fileEventId}); // eslint-disable-line camelcase
+        });
+        client.sendMessage = sendMsgFn;
+
+        const sendStateFn = jest.fn().mockImplementation((roomId: string, eventType: string, content: any, stateKey: string) => {
+            expect(roomId).toEqual(tree.roomId);
+            expect(eventType).toEqual(UNSTABLE_MSC3089_BRANCH.unstable); // test to ensure we're definitely using unstable
+            expect(stateKey).toEqual(fileEventId);
+            expect(content).toMatchObject({
+                active: true,
+                name: fileName,
+            });
+
+            return Promise.resolve(); // return value not used.
+        });
+        client.sendStateEvent = sendStateFn;
+
+        const buf = Uint8Array.from(Array.from(fileContents).map((_, i) => fileContents.charCodeAt(i)));
+
+        // We clone the file info just to make sure it doesn't get mutated for the test.
+        await tree.createFile(fileName, buf, Object.assign({}, fileInfo));
+
+        expect(uploadFn).toHaveBeenCalledTimes(1);
+        expect(sendMsgFn).toHaveBeenCalledTimes(1);
+        expect(sendStateFn).toHaveBeenCalledTimes(1);
+    });
+
+    it('should support getting files', () => {
+        const fileEventId = "$file";
+        const fileEvent = {forTest: true}; // MatrixEvent mock
+        room.currentState = {
+            getStateEvents: (eventType: string, stateKey?: string) => {
+                expect(eventType).toEqual(UNSTABLE_MSC3089_BRANCH.unstable); // test to ensure we're definitely using unstable
+                expect(stateKey).toEqual(fileEventId);
+                return fileEvent;
+            },
+        };
+
+        const file = tree.getFile(fileEventId);
+        expect(file).toBeDefined();
+        expect(file.indexEvent).toBe(fileEvent);
+    });
+
+    it('should return falsy for unknown files', () => {
+        const fileEventId = "$file";
+        room.currentState = {
+            getStateEvents: (eventType: string, stateKey?: string) => {
+                expect(eventType).toEqual(UNSTABLE_MSC3089_BRANCH.unstable); // test to ensure we're definitely using unstable
+                expect(stateKey).toEqual(fileEventId);
+                return null;
+            },
+        };
+
+        const file = tree.getFile(fileEventId);
+        expect(file).toBeFalsy();
+    });
+
+    it('should list files', () => {
+        const firstFile = {getContent: () => ({active: true})};
+        const secondFile = {getContent: () => ({active: false})}; // deliberately inactive
+        room.currentState = {
+            getStateEvents: (eventType: string, stateKey?: string) => {
+                expect(eventType).toEqual(UNSTABLE_MSC3089_BRANCH.unstable); // test to ensure we're definitely using unstable
+                expect(stateKey).toBeUndefined();
+                return [firstFile, secondFile];
+            },
+        };
+
+        const files = tree.listFiles();
+        expect(files).toBeDefined();
+        expect(files.length).toEqual(1);
+        expect(files[0].indexEvent).toBe(firstFile);
+    });
 });
diff --git a/src/@types/event.ts b/src/@types/event.ts
index 9e726de77..a4e11fe34 100644
--- a/src/@types/event.ts
+++ b/src/@types/event.ts
@@ -130,3 +130,25 @@ export const UNSTABLE_MSC3089_TREE_SUBTYPE = new UnstableValue("m.data_tree", "o
  * eventual removal.
  */
 export const UNSTABLE_MSC3089_LEAF = new UnstableValue("m.leaf", "org.matrix.msc3089.leaf");
+
+/**
+ * Branch (Leaf Reference) type for the index approach in a
+ * [MSC3089](https://github.com/matrix-org/matrix-doc/pull/3089) space-room. Note that this reference is
+ * UNSTABLE and subject to breaking changes, including its eventual removal.
+ */
+export const UNSTABLE_MSC3089_BRANCH = new UnstableValue("m.branch", "org.matrix.msc3089.branch");
+
+export interface IEncryptedFile {
+    url: string;
+    mimetype?: string;
+    key: {
+        alg: string;
+        key_ops: string[]; // eslint-disable-line camelcase
+        kty: string;
+        k: string;
+        ext: boolean;
+    };
+    iv: string;
+    hashes: {[alg: string]: string};
+    v: string;
+}
diff --git a/src/client.ts b/src/client.ts
index 0d4fa7795..65a42968d 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -4295,7 +4295,7 @@ export class MatrixClient extends EventEmitter {
      *    {@link module:models/event-timeline~EventTimeline} including the given
      *    event
      */
-    public getEventTimeline(timelineSet: EventTimelineSet, eventId: string): EventTimeline {
+    public getEventTimeline(timelineSet: EventTimelineSet, eventId: string): Promise<EventTimeline> {
         // don't allow any timeline support unless it's been enabled.
         if (!this.timelineSupport) {
             throw new Error("timeline support is disabled. Set the 'timelineSupport'" +
diff --git a/src/models/MSC3089Branch.ts b/src/models/MSC3089Branch.ts
new file mode 100644
index 000000000..655e374d8
--- /dev/null
+++ b/src/models/MSC3089Branch.ts
@@ -0,0 +1,102 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import { MatrixClient } from "../client";
+import { IEncryptedFile, UNSTABLE_MSC3089_BRANCH } from "../@types/event";
+import { MatrixEvent } from "./event";
+
+/**
+ * Represents a [MSC3089](https://github.com/matrix-org/matrix-doc/pull/3089) branch - a reference
+ * to a file (leaf) in the tree. Note that this is UNSTABLE and subject to breaking changes
+ * without notice.
+ */
+export class MSC3089Branch {
+    public constructor(private client: MatrixClient, public readonly indexEvent: MatrixEvent) {
+        // Nothing to do
+    }
+
+    /**
+     * The file ID.
+     */
+    public get id(): string {
+        return this.indexEvent.getStateKey();
+    }
+
+    /**
+     * Whether this branch is active/valid.
+     */
+    public get isActive(): boolean {
+        return this.indexEvent.getContent()["active"] === true;
+    }
+
+    private get roomId(): string {
+        return this.indexEvent.getRoomId();
+    }
+
+    /**
+     * Deletes the file from the tree.
+     * @returns {Promise<void>} Resolves when complete.
+     */
+    public async delete(): Promise<void> {
+        await this.client.sendStateEvent(this.roomId, UNSTABLE_MSC3089_BRANCH.name, {}, this.id);
+        await this.client.redactEvent(this.roomId, this.id);
+
+        // TODO: Delete edit history as well
+    }
+
+    /**
+     * Gets the name for this file.
+     * @returns {string} The name, or "Unnamed File" if unknown.
+     */
+    public getName(): string {
+        return this.indexEvent.getContent()['name'] || "Unnamed File";
+    }
+
+    /**
+     * Sets the name for this file.
+     * @param {string} name The new name for this file.
+     * @returns {Promise<void>} Resolves when complete.
+     */
+    public setName(name: string): Promise<void> {
+        return this.client.sendStateEvent(this.roomId, UNSTABLE_MSC3089_BRANCH.name, {
+            ...this.indexEvent.getContent(),
+            name: name,
+        }, this.id);
+    }
+
+    /**
+     * Gets information about the file needed to download it.
+     * @returns {Promise<{info: IEncryptedFile, httpUrl: string}>} Information about the file.
+     */
+    public async getFileInfo(): Promise<{ info: IEncryptedFile, httpUrl: string }> {
+        const room = this.client.getRoom(this.roomId);
+        if (!room) throw new Error("Unknown room");
+
+        const timeline = await this.client.getEventTimeline(room.getUnfilteredTimelineSet(), this.id);
+        if (!timeline) throw new Error("Failed to get timeline for room event");
+
+        const event = timeline.getEvents().find(e => e.getId() === this.id);
+        if (!event) throw new Error("Failed to find event");
+
+        // Sometimes the event context doesn't decrypt for us, so do that.
+        await this.client.decryptEventIfNeeded(event, {emit: false, isRetry: false});
+
+        const file = event.getContent()['file'];
+        const httpUrl = this.client.mxcUrlToHttp(file['url']);
+
+        return { info: file, httpUrl: httpUrl };
+    }
+}
diff --git a/src/models/MSC3089TreeSpace.ts b/src/models/MSC3089TreeSpace.ts
index b07fca706..153e4b494 100644
--- a/src/models/MSC3089TreeSpace.ts
+++ b/src/models/MSC3089TreeSpace.ts
@@ -15,11 +15,12 @@ limitations under the License.
 */
 
 import { MatrixClient } from "../client";
-import { EventType } from "../@types/event";
+import { EventType, IEncryptedFile, MsgType, UNSTABLE_MSC3089_BRANCH, UNSTABLE_MSC3089_LEAF } from "../@types/event";
 import { Room } from "./room";
 import { logger } from "../logger";
 import { MatrixEvent } from "./event";
 import { averageBetweenStrings, DEFAULT_ALPHABET, nextString, prevString } from "../utils";
+import { MSC3089Branch } from "./MSC3089Branch";
 
 /**
  * The recommended defaults for a tree space's power levels. Note that this
@@ -180,7 +181,7 @@ export class MSC3089TreeSpace {
         for (const child of children) {
             try {
                 const tree = this.client.unstableGetFileTreeSpace(child.getStateKey());
-                trees.push(tree);
+                if (tree) trees.push(tree);
             } catch (e) {
                 logger.warn("Unable to create tree space instance for listing. Are we joined?", e);
             }
@@ -378,4 +379,51 @@ export class MSC3089TreeSpace {
             order: newOrder,
         }, this.roomId);
     }
+
+    /**
+     * Creates (uploads) a new file to this tree. The file must have already been encrypted for the room.
+     * @param {string} name The name of the file.
+     * @param {ArrayBuffer} encryptedContents The encrypted contents.
+     * @param {Partial<IEncryptedFile>} info The encrypted file information.
+     * @returns {Promise<void>} Resolves when uploaded.
+     */
+    public async createFile(name: string, encryptedContents: ArrayBuffer, info: Partial<IEncryptedFile>): Promise<void> {
+        const mxc = await this.client.uploadContent(new Blob([encryptedContents]), {
+            includeFilename: false,
+            onlyContentUri: true,
+        });
+        info.url = mxc;
+
+        const res = await this.client.sendMessage(this.roomId, {
+            msgtype: MsgType.File,
+            body: name,
+            url: mxc,
+            file: info,
+            [UNSTABLE_MSC3089_LEAF.name]: {},
+        });
+
+        await this.client.sendStateEvent(this.roomId, UNSTABLE_MSC3089_BRANCH.name, {
+            active: true,
+            name: name,
+        }, res['event_id']);
+    }
+
+    /**
+     * Retrieves a file from the tree.
+     * @param {string} fileEventId The event ID of the file.
+     * @returns {MSC3089Branch} The file, or falsy if not found.
+     */
+    public getFile(fileEventId: string): MSC3089Branch {
+        const branch = this.room.currentState.getStateEvents(UNSTABLE_MSC3089_BRANCH.name, fileEventId);
+        return branch ? new MSC3089Branch(this.client, branch) : null;
+    }
+
+    /**
+     * Gets an array of all known files for the tree.
+     * @returns {MSC3089Branch[]} The known files. May be empty, but not null.
+     */
+    public listFiles(): MSC3089Branch[] {
+        const branches = this.room.currentState.getStateEvents(UNSTABLE_MSC3089_BRANCH.name) ?? [];
+        return branches.map(e => new MSC3089Branch(this.client, e)).filter(b => b.isActive);
+    }
 }