diff --git a/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSet.java b/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSet.java
index 8f82698..04560d7 100644
--- a/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSet.java
+++ b/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSet.java
@@ -298,6 +298,16 @@
     return children instanceof ListenableFuture;
   }
 
+  /**
+   * Returns true if the contents of this set are currently available in memory.
+   *
+   * <p>Only returns false if this set {@link #isFromStorage} and the contents are not fully
+   * deserialized.
+   */
+  public boolean isReady() {
+    return !isFromStorage() || ((ListenableFuture<Object[]>) children).isDone();
+  }
+
   /** Returns the single element; only call this if {@link #isSingleton} returns true. */
   public E getSingleton() {
     Preconditions.checkState(isSingleton());
diff --git a/src/test/java/com/google/devtools/build/lib/collect/nestedset/NestedSetImplTest.java b/src/test/java/com/google/devtools/build/lib/collect/nestedset/NestedSetImplTest.java
index 0752f9e..3d40e9c 100644
--- a/src/test/java/com/google/devtools/build/lib/collect/nestedset/NestedSetImplTest.java
+++ b/src/test/java/com/google/devtools/build/lib/collect/nestedset/NestedSetImplTest.java
@@ -324,4 +324,19 @@
     NestedSet<?> inMemoryNestedSet = NestedSetBuilder.create(Order.STABLE_ORDER, "a", "b");
     assertThat(inMemoryNestedSet.isFromStorage()).isFalse();
   }
+
+  @Test
+  public void isReady_inMemory() {
+    NestedSet<?> inMemoryNestedSet = NestedSetBuilder.create(Order.STABLE_ORDER, "a", "b");
+    assertThat(inMemoryNestedSet.isReady()).isTrue();
+  }
+
+  @Test
+  public void isReady_fromStorage() {
+    SettableFuture<Object[]> future = SettableFuture.create();
+    NestedSet<?> deserializingNestedSet = NestedSet.withFuture(Order.STABLE_ORDER, future);
+    assertThat(deserializingNestedSet.isReady()).isFalse();
+    future.set(new Object[] {"a", "b"});
+    assertThat(deserializingNestedSet.isReady()).isTrue();
+  }
 }