Big Brother 15 is the fifthteenth season of the American reality television show, "Big Brother". It began airing on CBS starting on June 26, 2013 on Sundays, Tuesdays and Wednesdays. It will continue to air on CBS until September 18, 2013. It is being called the "longest season to date" in "Big Brother" history, lasting a total of 90 days. This season features sixteen HouseGuests. 