THE GANG FINDS OUT THAT ROBIN AND BARNEY ARE CARRYING ON A SECRET ROMANCE, ON THE FIFTH SEASON PREMIERE OF "HOW I MET YOUR MOTHER," MONDAY, SEPT. 21

"Definitions" - When the gang finds out that Barney and Robin are hesitant to define their relationship, Lily forces them to confront their biggest fear...becoming boyfriend/girlfriend. Meanwhile, Ted is anxious about teaching his first lecture at Columbia, on the fifth season premiere of HOW I MET YOUR MOTHER, Monday, Sept. 21 (8:00-8:30 PM, ET/PT) on the CBS Television Network.

SERIES REGULARS:

Ted.............................................. Josh Radnor
Marshall........................................ Jason Segel
Barney................................ Neil Patrick Harris
Lily........................................ Alyson Hannigan
Robin ..................................... Cobie Smulders

RECURRING CAST

Narrator.......................................... Bob Saget

GUEST CAST:

Brad....................................... Joe Manganiello
Professor Calzonetti............Dale E. Turner
Girl #2.............................Laura Ornelas
Guy #2........................................... Abhi Sinha
Girl................................Kim Matula
Guy..............................Brett Ryback
Student........................Michael Busch

WRITTEN BY: Carter Bays and Craig Thomas

DIRECTED BY: Pamela Fryman

RATING: To Be Announced