diff --git a/back/store.go b/back/store.go
index 587f594..5df6586 100644
--- a/back/store.go
+++ b/back/store.go
@@ -91,10 +91,25 @@ const schema = `
 
 	CREATE TABLE response_time (
 		response_id INTEGER PRIMARY KEY,
+		date DATE NOT NULL,
 		time INTEGER NOT NULL,
 
-		CHECK (0 <= time < 24)
-	);`
+		CHECK (0 <= time < 24),
+		UNIQUE (response_id, date, time)
+	);
+	
+	CREATE TRIGGER enforce_valid_response_dates
+	BEFORE INSERT ON response_time
+	BEGIN
+		SELECT
+			CASE
+				WHEN NEW.date BETWEEN event.earliest_date AND event.latest_date
+					THEN RAISE(ABORT, 'response date is out of range')
+			END
+		FROM response
+		JOIN event ON response.event_id = event.id
+		WHERE response.id = NEW.response_id;
+	END;`
 
 func (s *Store) createSchema() error {
 	conn := s.pool.Get(context.Background())
@@ -224,3 +239,41 @@ func (s *Store) GetEventResponses(ctx context.Context, query GetEventResponsesQu
 	// TODO return an error if the event does not exist?
 	return result, err
 }
+
+type CreateEventResponseCommand struct {
+	EventAlphaID string
+	DateHours    map[time.Time]int
+}
+
+type CreateEventResponseResult struct {
+	ResponseAlphaID string
+}
+
+func (s *Store) CreateEventResponse(ctx context.Context, cmd CreateEventResponseCommand) (result CreateEventResponseResult, err error) {
+	const responseAlphaIDLength = 10
+
+	conn := s.pool.Get(ctx)
+	defer s.pool.Put(conn)
+
+	defer sqlitex.Save(conn)(&err)
+	responseAlphaID, err := s.genString(responseAlphaIDLength)
+	if err != nil {
+		return CreateEventResponseResult{}, err
+	}
+
+	// Create response
+	const responseQuery = `
+		INSERT INTO response(event_id, alpha_id)
+			SELECT event.id AS event_id, ? AS alpha_id
+			FROM event
+			WHERE event.alpha_id = ?;`
+	err = sqlitex.Exec(conn, responseQuery, nil, responseAlphaID, cmd.EventAlphaID)
+	if err != nil {
+		return CreateEventResponseResult{}, err
+	}
+	// TODO Create response times
+
+	return CreateEventResponseResult{
+		ResponseAlphaID: responseAlphaID,
+	}, nil
+}
diff --git a/back/store_test.go b/back/store_test.go
index d365d1a..dab1098 100644
--- a/back/store_test.go
+++ b/back/store_test.go
@@ -44,3 +44,58 @@ func TestCreateEvent(t *testing.T) {
 	is.True(metadataResult.EarliestDate.Equal(earliest))
 	is.True(metadataResult.LatestDate.Equal(latest))
 }
+
+func TestGetEventResponses(t *testing.T) {
+	store, err := back.NewMemoryStore(back.SecureGenString)
+	is.New(t).NoErr(err)
+
+	createEvent := func(is *is.I) (eventID string) {
+		event, err := store.CreateEvent(context.Background(), back.CreateEventCommand{
+			Name: "blah",
+			Description: "stuff happening",
+			EarliestDate: time.Now(),
+			LatestDate: time.Now().AddDate(0,0,1),
+		})
+		is.NoErr(err)
+		return event.AlphaID
+	}
+
+	getTotalResponses := func(is *is.I, eventID string) int {
+		responses, err := store.GetEventResponses(context.Background(), back.GetEventResponsesQuery{
+			AlphaID: eventID,
+		})
+		is.NoErr(err)
+		return responses.TotalResponses
+	}
+
+	createEmptyResponse := func(is *is.I, eventID string) {
+		_, err = store.CreateEventResponse(context.Background(), back.CreateEventResponseCommand{
+			EventAlphaID: eventID,
+		})
+		is.NoErr(err)
+	}
+
+	t.Run("TotalResponses counts the number of responses created", func(t *testing.T) {
+		is := is.New(t)
+
+		eventID := createEvent(is)
+		is.Equal(getTotalResponses(is, eventID), 0)
+		const respondTimes = 5
+		for i := 1; i <= respondTimes; i++ {
+			createEmptyResponse(is, eventID)
+			is.Equal(getTotalResponses(is, eventID), i)
+		}
+	})
+
+	t.Run("TotalResponses does not count responses to other events", func(t *testing.T) {
+		is := is.New(t)
+
+		eventID := createEvent(is)
+		createEmptyResponse(is, eventID)
+
+		// Create a response to another event
+		createEmptyResponse(is, createEvent(is))
+
+		is.Equal(getTotalResponses(is, eventID), 1)
+	})
+}
\ No newline at end of file