diff --git a/walkthroughs/week-5-tdd/project/src/main/java/com/google/sps/FindMeetingQuery.java b/walkthroughs/week-5-tdd/project/src/main/java/com/google/sps/FindMeetingQuery.java
index 569c4eb..4c70f2b 100644
--- a/walkthroughs/week-5-tdd/project/src/main/java/com/google/sps/FindMeetingQuery.java
+++ b/walkthroughs/week-5-tdd/project/src/main/java/com/google/sps/FindMeetingQuery.java
@@ -32,7 +32,24 @@ public final class FindMeetingQuery {
    * @return A collection of available times.
    */
   public Collection<TimeRange> query(Collection<Event> events, MeetingRequest request) {
-    List<TimeRange> unavailableTimeRanges = getUnavailableTimes(events, request.getAttendees());
+    Collection<TimeRange> suggestedTimeRanges = findTimeForMeetingRequest(events, request, true);
+
+    if (suggestedTimeRanges.size() == 0 && request.getAttendees().size() != 0) {
+      suggestedTimeRanges = findTimeForMeetingRequest(events, request, false);
+    }
+
+    return suggestedTimeRanges;
+  }
+
+  public Collection<TimeRange> findTimeForMeetingRequest(Collection<Event> events, MeetingRequest request, 
+      boolean includeOptionalAttendees) {
+    List<String> attendees = new ArrayList<>(request.getAttendees());
+
+    if (includeOptionalAttendees) {
+      attendees.addAll(request.getOptionalAttendees());
+    }
+
+    List<TimeRange> unavailableTimeRanges = getUnavailableTimes(events, attendees);
     List<TimeRange> suggestedTimeRanges = findAvailableTimeRanges(unavailableTimeRanges, request.getDuration());
 
     return suggestedTimeRanges;
diff --git a/walkthroughs/week-5-tdd/project/src/test/java/com/google/sps/FindMeetingQueryTest.java b/walkthroughs/week-5-tdd/project/src/test/java/com/google/sps/FindMeetingQueryTest.java
index 9235153..d58c149 100644
--- a/walkthroughs/week-5-tdd/project/src/test/java/com/google/sps/FindMeetingQueryTest.java
+++ b/walkthroughs/week-5-tdd/project/src/test/java/com/google/sps/FindMeetingQueryTest.java
@@ -34,6 +34,7 @@ public final class FindMeetingQueryTest {
   // Some people that we can use in our tests.
   private static final String PERSON_A = "Person A";
   private static final String PERSON_B = "Person B";
+  private static final String PERSON_C = "Person C";
 
   // All dates are the first day of the year 2020.
   private static final int TIME_0800AM = TimeRange.getTimeInMinutes(8, 0);
@@ -43,6 +44,7 @@ public final class FindMeetingQueryTest {
   private static final int TIME_1000AM = TimeRange.getTimeInMinutes(10, 0);
   private static final int TIME_1100AM = TimeRange.getTimeInMinutes(11, 00);
 
+  private static final int DURATION_15_MINUTES = 15;
   private static final int DURATION_30_MINUTES = 30;
   private static final int DURATION_60_MINUTES = 60;
   private static final int DURATION_90_MINUTES = 90;
@@ -121,6 +123,51 @@ public void everyAttendeeIsConsidered() {
     Assert.assertEquals(expected, actual);
   }
 
+  @Test
+  public void optionalAttendeesAreIgnoredIfBusy() {
+    Collection<Event> events = Arrays.asList(
+        new Event("Event 1", TimeRange.fromStartDuration(TIME_0800AM, DURATION_30_MINUTES),
+            Arrays.asList(PERSON_A)),
+        new Event("Event 2", TimeRange.fromStartDuration(TIME_0900AM, DURATION_30_MINUTES),
+            Arrays.asList(PERSON_B)),
+        new Event("Event 3", TimeRange.WHOLE_DAY,
+            Arrays.asList(PERSON_C)));
+    
+    MeetingRequest request =
+        new MeetingRequest(Arrays.asList(PERSON_A, PERSON_B), DURATION_30_MINUTES);
+    request.addOptionalAttendee(PERSON_C);
+
+    Collection<TimeRange> actual = query.query(events, request);
+    Collection<TimeRange> expected =
+        Arrays.asList(TimeRange.fromStartEnd(TimeRange.START_OF_DAY, TIME_0800AM, false),
+            TimeRange.fromStartEnd(TIME_0830AM, TIME_0900AM, false),
+            TimeRange.fromStartEnd(TIME_0930AM, TimeRange.END_OF_DAY, true));
+
+    Assert.assertEquals(expected, actual);
+  }
+
+  @Test
+  public void optionalAttendeesAreConsideredIfAvailable() {
+    Collection<Event> events = Arrays.asList(
+        new Event("Event 1", TimeRange.fromStartDuration(TIME_0800AM, DURATION_30_MINUTES),
+            Arrays.asList(PERSON_A)),
+        new Event("Event 2", TimeRange.fromStartDuration(TIME_0900AM, DURATION_30_MINUTES),
+            Arrays.asList(PERSON_B)),
+        new Event("Event 3", TimeRange.fromStartDuration(TIME_0830AM, DURATION_30_MINUTES),
+            Arrays.asList(PERSON_C)));
+    
+    MeetingRequest request =
+        new MeetingRequest(Arrays.asList(PERSON_A, PERSON_B), DURATION_30_MINUTES);
+    request.addOptionalAttendee(PERSON_C);
+
+    Collection<TimeRange> actual = query.query(events, request);
+    Collection<TimeRange> expected =
+        Arrays.asList(TimeRange.fromStartEnd(TimeRange.START_OF_DAY, TIME_0800AM, false),
+            TimeRange.fromStartEnd(TIME_0930AM, TimeRange.END_OF_DAY, true));
+
+    Assert.assertEquals(expected, actual);
+  }
+
   @Test
   public void overlappingEvents() {
     // Have an event for each person, but have their events overlap. We should only see two options.
@@ -223,6 +270,65 @@ public void justEnoughRoom() {
     Assert.assertEquals(expected, actual);
   }
 
+  @Test
+  public void optionalAttendeesIgnoredIfNotEnoughTime() {
+    Collection<Event> events = Arrays.asList(
+        new Event("Event 1", TimeRange.fromStartEnd(TimeRange.START_OF_DAY, TIME_0830AM, false),
+            Arrays.asList(PERSON_A)),
+        new Event("Event 2", TimeRange.fromStartEnd(TIME_0900AM, TimeRange.END_OF_DAY, true),
+            Arrays.asList(PERSON_A)),
+        new Event("Event 3", TimeRange.fromStartDuration(TIME_0830AM, DURATION_15_MINUTES),
+            Arrays.asList(PERSON_B)));
+
+    MeetingRequest request = new MeetingRequest(Arrays.asList(PERSON_A), DURATION_30_MINUTES);
+    request.addOptionalAttendee(PERSON_B);
+
+    Collection<TimeRange> actual = query.query(events, request);
+    Collection<TimeRange> expected =
+        Arrays.asList(TimeRange.fromStartDuration(TIME_0830AM, DURATION_30_MINUTES));
+
+    Assert.assertEquals(expected, actual);
+  }
+
+  @Test
+  public void findsTimeWithOnlyOptionalAttendees() {
+    Collection<Event> events = Arrays.asList(
+        new Event("Event 1", TimeRange.fromStartDuration(TIME_0800AM, DURATION_30_MINUTES),
+            Arrays.asList(PERSON_A)),
+        new Event("Event 2", TimeRange.fromStartDuration(TIME_0900AM, DURATION_30_MINUTES),
+            Arrays.asList(PERSON_B)));
+
+    MeetingRequest request = new MeetingRequest(new ArrayList<>(), DURATION_30_MINUTES);
+    request.addOptionalAttendee(PERSON_A);
+    request.addOptionalAttendee(PERSON_B);
+
+    Collection<TimeRange> actual = query.query(events, request);
+    Collection<TimeRange> expected =
+        Arrays.asList(TimeRange.fromStartEnd(TimeRange.START_OF_DAY, TIME_0800AM, false),
+            TimeRange.fromStartEnd(TIME_0830AM, TIME_0900AM, false),
+            TimeRange.fromStartEnd(TIME_0930AM, TimeRange.END_OF_DAY, true));
+
+    Assert.assertEquals(expected, actual);
+  }
+
+  @Test
+  public void findsNoTimeWithOnlyBusyOptionalAttendees() {
+    Collection<Event> events = Arrays.asList(
+        new Event("Event 1", TimeRange.fromStartEnd(TimeRange.START_OF_DAY, TIME_0830AM, false),
+            Arrays.asList(PERSON_A)),
+        new Event("Event 2", TimeRange.fromStartEnd(TIME_0830AM, TimeRange.END_OF_DAY, true),
+            Arrays.asList(PERSON_B)));
+
+    MeetingRequest request = new MeetingRequest(new ArrayList<>(), DURATION_30_MINUTES);
+    request.addOptionalAttendee(PERSON_A);
+    request.addOptionalAttendee(PERSON_B);
+
+    Collection<TimeRange> actual = query.query(events, request);
+    Collection<TimeRange> expected = Arrays.asList();
+
+    Assert.assertEquals(expected, actual);
+  }
+
   @Test
   public void ignoresPeopleNotAttending() {
     // Add an event, but make the only attendee someone different from the person looking to book