diff --git a/rxjava-core/src/main/java/rx/concurrency/TestScheduler.java b/rxjava-core/src/main/java/rx/concurrency/TestScheduler.java
new file mode 100644
index 0000000000..27d3c18bd4
--- /dev/null
+++ b/rxjava-core/src/main/java/rx/concurrency/TestScheduler.java
@@ -0,0 +1,94 @@
+/**
+ * Copyright 2013 Netflix, Inc.
+ * 
+ * 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.
+ */
+package rx.concurrency;
+
+import java.util.Comparator;
+import java.util.PriorityQueue;
+import java.util.Queue;
+import java.util.concurrent.TimeUnit;
+
+import rx.Subscription;
+import rx.subscriptions.Subscriptions;
+import rx.util.functions.Func0;
+
+public class TestScheduler extends AbstractScheduler {
+    private final Queue<TimedAction> queue = new PriorityQueue<TimedAction>(11, new CompareActionsByTime());
+    
+    private static class TimedAction {
+        private final long time;
+        private final Func0<Subscription> action;
+
+        private TimedAction(long time, Func0<Subscription> action) {
+            this.time = time;
+            this.action = action;
+        }
+        
+        @Override
+        public String toString() {
+            return String.format("TimedAction(time = %d, action = %s)", time, action.toString());
+        }
+    }
+    
+    private static class CompareActionsByTime implements Comparator<TimedAction> {
+      @Override
+      public int compare(TimedAction action1, TimedAction action2) {
+          return Long.valueOf(action1.time).compareTo(Long.valueOf(action2.time));
+      }
+    }
+    
+    private long time;
+    
+    @Override
+    public Subscription schedule(Func0<Subscription> action) {
+        return schedule(action, 0L, TimeUnit.NANOSECONDS);
+    }
+
+    @Override
+    public Subscription schedule(Func0<Subscription> action, long dueTime, TimeUnit unit) {
+        queue.add(new TimedAction(now() + unit.toNanos(dueTime), action));
+        return Subscriptions.empty();
+    }
+    
+    @Override
+    public long now() {
+        return time;
+    }
+
+    public void advanceTimeBy(long dueTime, TimeUnit unit) {
+        advanceTimeTo(time + unit.toNanos(dueTime), TimeUnit.NANOSECONDS);
+    }
+    
+    public void advanceTimeTo(long dueTime, TimeUnit unit) {
+        long targetTime = unit.toNanos(dueTime);
+        triggerActions(targetTime);
+    }
+
+    public void triggerActions() {
+      triggerActions(time);
+    }
+    
+    private void triggerActions(long targetTimeInNanos) {
+        while (! queue.isEmpty()) {
+            TimedAction current = queue.peek();
+            if (current.time > targetTimeInNanos) {
+                break;
+            }
+            time = current.time;
+            queue.remove();
+            current.action.call();
+        }
+    }
+}
diff --git a/rxjava-core/src/main/java/rx/operators/OperationInterval.java b/rxjava-core/src/main/java/rx/operators/OperationInterval.java
new file mode 100644
index 0000000000..19a3736826
--- /dev/null
+++ b/rxjava-core/src/main/java/rx/operators/OperationInterval.java
@@ -0,0 +1,140 @@
+/**
+ * Copyright 2013 Netflix, Inc.
+ * 
+ * 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.
+ */
+package rx.operators;
+
+import static org.mockito.Matchers.*;
+import static org.mockito.Mockito.*;
+
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.InOrder;
+
+import rx.Observable;
+import rx.Observer;
+import rx.Scheduler;
+import rx.Subscription;
+import rx.concurrency.Schedulers;
+import rx.concurrency.TestScheduler;
+import rx.subscriptions.Subscriptions;
+import rx.util.functions.Action0;
+import rx.util.functions.Func1;
+
+/**
+ * Returns an observable sequence that produces a value after each period.
+ * The value starts at 0 and counts up each period.
+ */
+public final class OperationInterval {
+
+    /**
+     * Creates an event each time interval.
+     */
+    public static Func1<Observer<Long>, Subscription> interval(long interval, TimeUnit unit) {
+        return new Interval(interval, unit, Schedulers.executor(Executors.newSingleThreadScheduledExecutor()));
+    }
+
+    /**
+     * Creates an event each time interval.
+     */
+    public static Func1<Observer<Long>, Subscription> interval(long interval, TimeUnit unit, Scheduler scheduler) {
+        return new Interval(interval, unit, scheduler);
+    }
+
+    private static class Interval implements Func1<Observer<Long>, Subscription> {
+        private final long interval;
+        private final TimeUnit unit;
+        private final Scheduler scheduler;
+        
+        private long currentValue;
+        private final AtomicBoolean complete = new AtomicBoolean();
+
+        private Interval(long interval, TimeUnit unit, Scheduler scheduler) {
+            this.interval = interval;
+            this.unit = unit;
+            this.scheduler = scheduler;
+        }
+
+        @Override
+        public Subscription call(final Observer<Long> observer) {
+            scheduler.schedule(new IntervalAction(observer), interval, unit);
+            return Subscriptions.create(new Action0() {
+                @Override
+                public void call() {
+                    complete.set(true);
+                }
+            });
+        }
+        
+        private class IntervalAction implements Action0 {
+            private final Observer<Long> observer;
+            
+            private IntervalAction(Observer<Long> observer) {
+                this.observer = observer;
+            }
+            
+            @Override
+            public void call() {
+                if (complete.get()) {
+                    observer.onCompleted();
+                } else {
+                    observer.onNext(currentValue);
+                    currentValue++;
+                    scheduler.schedule(this, interval, unit);
+                }
+            }
+        }
+    }
+    
+    public static class UnitTest {
+        private TestScheduler scheduler;
+        private Observer<Long> observer;
+        
+        @Before
+        @SuppressWarnings("unchecked") // due to mocking
+        public void before() {
+            scheduler = new TestScheduler();
+            observer = mock(Observer.class);
+        }
+        
+        @Test
+        public void testInterval() {
+            Observable<Long> w = Observable.create(OperationInterval.interval(1, TimeUnit.SECONDS, scheduler));
+            Subscription sub = w.subscribe(observer);
+            
+            verify(observer, never()).onNext(0L);
+            verify(observer, never()).onCompleted();
+            verify(observer, never()).onError(any(Exception.class));
+            
+            scheduler.advanceTimeTo(2, TimeUnit.SECONDS);
+
+            InOrder inOrder = inOrder(observer);
+            inOrder.verify(observer, times(1)).onNext(0L);
+            inOrder.verify(observer, times(1)).onNext(1L);
+            inOrder.verify(observer, never()).onNext(2L);
+            verify(observer, never()).onCompleted();
+            verify(observer, never()).onError(any(Exception.class));
+            
+            sub.unsubscribe();
+            scheduler.advanceTimeTo(4, TimeUnit.SECONDS);
+            verify(observer, never()).onNext(2L);
+            verify(observer, times(1)).onCompleted();
+            verify(observer, never()).onError(any(Exception.class));
+        }
+    }
+}