diff --git a/index.bs b/index.bs
index a45953a45..35808e914 100644
--- a/index.bs
+++ b/index.bs
@@ -509,7 +509,6 @@ it would look like
     constructor(stream)
 
     get closed()
-    get isActive()
 
     cancel(reason)
     read()
@@ -580,19 +579,6 @@ Instances of <code>ReadableStreamReader</code> are created with the internal slo
   <li> Return <b>this</b>@\[[closedPromise]].
 </ol>
 
-<h5 id="reader-is-active">get isActive</h5>
-
-<div class="note">
-  The <code>isActive</code> getter returns whether or not the stream reader is currently
-  <a lt="active reader">active</a>.
-</div>
-
-<ol>
-  <li> If IsReadableStreamReader(<b>this</b>) is <b>false</b>, throw a <b>TypeError</b> exception.
-  <li> If <b>this</b>@\[[ownerReadableStream]] is <b>undefined</b>, return <b>false</b>; otherwise, return
-    <b>true</b>.
-</ol>
-
 <h5 id="reader-cancel">cancel(reason)</h5>
 
 <div class="note">
diff --git a/reference-implementation/lib/readable-stream.js b/reference-implementation/lib/readable-stream.js
index 4b6f38979..43097e717 100644
--- a/reference-implementation/lib/readable-stream.js
+++ b/reference-implementation/lib/readable-stream.js
@@ -180,14 +180,6 @@ class ReadableStreamReader {
     return this._closedPromise;
   }
 
-  get isActive() {
-    if (IsReadableStreamReader(this) === false) {
-      throw new TypeError('ReadableStreamReader.prototype.isActive can only be used on a ReadableStreamReader');
-    }
-
-    return this._ownerReadableStream !== undefined;
-  }
-
   cancel(reason) {
     if (IsReadableStreamReader(this) === false) {
       return Promise.reject(
diff --git a/reference-implementation/test/brand-checks.js b/reference-implementation/test/brand-checks.js
index 665376a1b..e98705efa 100644
--- a/reference-implementation/test/brand-checks.js
+++ b/reference-implementation/test/brand-checks.js
@@ -41,7 +41,6 @@ function realWritableStream() {
 function fakeReadableStreamReader() {
   return {
     get closed() { return Promise.resolve(); },
-    get isActive() { return false; },
     cancel(reason) { return Promise.resolve(); },
     read() { return Promise.resolve({ value: undefined, done: true }); },
     releaseLock() { return; }
@@ -161,12 +160,6 @@ test('ReadableStreamReader.prototype.closed enforces a brand check', t => {
   getterRejects(t, ReadableStreamReader.prototype, 'closed', realReadableStream());
 });
 
-test('ReadableStreamReader.prototype.isActive enforces a brand check', t => {
-  t.plan(2);
-  getterThrows(t, ReadableStreamReader.prototype, 'isActive', fakeReadableStreamReader());
-  getterThrows(t, ReadableStreamReader.prototype, 'isActive', realReadableStream());
-});
-
 test('ReadableStreamReader.prototype.cancel enforces a brand check', t => {
   t.plan(2);
   methodRejects(t, ReadableStreamReader.prototype, 'cancel', fakeReadableStreamReader());
diff --git a/reference-implementation/test/readable-stream-reader.js b/reference-implementation/test/readable-stream-reader.js
index 9223a7f87..c67f9ee01 100644
--- a/reference-implementation/test/readable-stream-reader.js
+++ b/reference-implementation/test/readable-stream-reader.js
@@ -68,11 +68,8 @@ test('Reading from a reader for an empty stream will wait until a chunk is avail
   });
   const reader = rs.getReader();
 
-  t.equal(reader.isActive, true, 'reader is active to start with');
-
   reader.read().then(result => {
     t.deepEqual(result, { value: 'a', done: false }, 'read() should fulfill with the enqueued chunk');
-    t.equal(reader.isActive, true, 'reader is still active');
     t.end();
   });
 
@@ -85,7 +82,7 @@ test('cancel() on a reader releases the reader before calling through', t => {
   const passedReason = new Error('it wasn\'t the right time, sorry');
   const rs = new ReadableStream({
     cancel(reason) {
-      t.equal(reader.isActive, false, 'reader should be released by the time underlying source cancel is called');
+      t.doesNotThrow(() => rs.getReader(), 'should be able to get another reader without error');
       t.equal(reason, passedReason, 'the cancellation reason is passed through to the underlying source');
     }
   });
@@ -109,14 +106,14 @@ test('closed should be fulfilled after stream is closed (.closed access before a
 
   const reader = rs.getReader();
   reader.closed.then(() => {
-    t.equal(reader.isActive, false, 'reader is no longer active when reader closed is fulfilled');
+    t.pass('reader closed should be fulfilled');
   });
 
   doClose();
 });
 
 test('closed should be fulfilled after reader releases its lock (multiple stream locks)', t => {
-  t.plan(4);
+  t.plan(2);
 
   let doClose;
   const rs = new ReadableStream({
@@ -133,13 +130,11 @@ test('closed should be fulfilled after reader releases its lock (multiple stream
   doClose();
 
   reader1.closed.then(() => {
-    t.equal(reader1.isActive, false, 'reader1 is no longer active when reader1 closed is fulfilled');
-    t.equal(reader2.isActive, false, 'reader2 is no longer active when reader1 closed is fulfilled');
+    t.pass('reader1 closed should be fulfilled');
   });
 
   reader2.closed.then(() => {
-    t.equal(reader1.isActive, false, 'reader1 is no longer active when reader2 closed is fulfilled');
-    t.equal(reader2.isActive, false, 'reader2 is no longer active when reader2 closed is fulfilled');
+    t.pass('reader2 closed should be fulfilled');
   });
 });
 
@@ -164,18 +159,24 @@ test('Multiple readers can access the stream in sequence', t => {
 });
 
 test('Cannot use an already-released reader to unlock a stream again', t => {
-  t.plan(2);
+  t.plan(1);
 
-  const rs = new ReadableStream();
+  const rs = new ReadableStream({
+    start(enqueue) {
+      enqueue('a');
+    }
+  });
 
   const reader1 = rs.getReader();
   reader1.releaseLock();
 
   const reader2 = rs.getReader();
-  t.equal(reader2.isActive, true, 'reader2 state is active before releasing reader1');
 
   reader1.releaseLock();
-  t.equal(reader2.isActive, true, 'reader2 state is still active after releasing reader1 again');
+  reader2.read().then(result => {
+    t.deepEqual(result, { value: 'a', done: false },
+      'read() should still work on reader2 even after reader1 is released');
+  });
 });
 
 test('cancel() on a released reader is a no-op and does not pass through', t => {
diff --git a/reference-implementation/test/templated/readable-stream-empty-reader.js b/reference-implementation/test/templated/readable-stream-empty-reader.js
index c4d6fc0a9..795363e67 100644
--- a/reference-implementation/test/templated/readable-stream-empty-reader.js
+++ b/reference-implementation/test/templated/readable-stream-empty-reader.js
@@ -78,17 +78,15 @@ export default (label, factory) => {
     );
 
     t.throws(() => reader.releaseLock(), /TypeError/, 'releaseLock should throw a TypeError');
-    t.equal(reader.isActive, true, 'the reader should still be active');
 
     setTimeout(() => t.end(), 50);
   });
 
   test('releasing the lock should cause further read() calls to resolve as if the stream is closed', t => {
-    t.plan(3);
+    t.plan(2);
     const { reader } = factory();
 
     reader.releaseLock();
-    t.equal(reader.isActive, false, 'the reader should no longer be active');
 
     reader.read().then(r =>
       t.deepEqual(r, { value: undefined, done: true }, 'first read() should return closed result'));
@@ -97,34 +95,29 @@ export default (label, factory) => {
   });
 
   test('releasing the lock should cause closed to fulfill', t => {
-    t.plan(3);
+    t.plan(2);
     const { reader } = factory();
 
     reader.closed.then(v => t.equal(v, undefined, 'reader.closed got before release should fulfill with undefined'));
 
     reader.releaseLock();
-    t.equal(reader.isActive, false, 'the reader should no longer be active');
 
     reader.closed.then(v => t.equal(v, undefined, 'reader.closed got after release should fulfill with undefined'));
   });
 
-  test('canceling via the reader should cause the reader to become inactive', t => {
-    t.plan(3);
+  test('canceling via the reader should cause the reader to act closed', t => {
+    t.plan(1);
     const { reader } = factory();
 
-    t.equal(reader.isActive, true, 'the reader should be active before releasing it');
     reader.cancel();
-    t.equal(reader.isActive, false, 'the reader should no longer be active');
     reader.read().then(r => t.deepEqual(r, { value: undefined, done: true },
       'read()ing from the reader should give a done result'))
   });
 
   test('canceling via the stream should fail', t => {
-    t.plan(3);
+    t.plan(1);
     const { stream, reader } = factory();
 
-    t.equal(reader.isActive, true, 'the reader should be active before releasing it');
     stream.cancel().catch(e => t.equal(e.constructor, TypeError, 'cancel() should reject with a TypeError'));
-    t.equal(reader.isActive, true, 'the reader should still be active');
   });
 };