Big Brother 15 is the fifteenth season of the American reality television series Big Brother. The season premiered on CBS on June 26, 2013 and will conclude in September 18, 2013 the same year. It has been billed as the longest season to date, and is going to last for a total of 90 days. This season is also set to feature sixteen HouseGuests, tying it for the most HouseGuests to compete in a single season. Unlike the previous two seasons, all of the competing HouseGuests are new to the series.

The premise of the series remained largely unchanged from previous editions of the series, in which a group of contestants, known as "HouseGuests," compete to win the series by voting each other off and being the last HouseGuest remaining. One HouseGuest, known as the Head of Household, must nominate two of their fellow HouseGuests for eviction. The winner of the Power of Veto can remove one of the nominees from the block, forcing the HoH to nominate another HouseGuest. The HouseGuests then vote to evict one of the nominees, and the HouseGuest with the most votes is evicted. When only two HouseGuests remained, the last seven evicted HouseGuests, known as the Jury of Seven, would decide which of them would win the $500,000 prize. A HouseGuest can be expelled from the show for breaking rules, such as engaging in violent and disruptive behavior. This season introduced the "M.V.P." twist, in which viewers would select one HouseGuest each week to earn the right to nominate one HouseGuest. This is in addition to the Head of Household nominating two HouseGuests per week, increasing the number of nominated HouseGuests to three. Though the number of nominations increased, only one of the nominees would be evicted each week.

Summary:

On Day 1, the original sixteen HouseGuests entered the house. Howard, Jeremy, and Spencer quickly formed an alliance, while Jeremy also formed an alliance with David and Jessie minutes later. The HouseGuests were later called to the living room, and learned that there would be a total of three nominations each week, though it was confirmed that the Head of Household would only nominate two of these nominees for eviction. Following this, HouseGuests competed in the "Popsicle Factory" Head of Household competition. For this competition, the HouseGuests were required to hang onto a fake Popsicle suspended in the air while being sprayed with colored water; the last HouseGuest remaining would be the first Head of Household. McCrae was the winner. During the competition, Jeremy won a Never-Not pass, meaning he was not eligible to become a Have-Not during his time in the game. Upon returning inside, the HouseGuests learned of the M.V.P. twist, in which the viewers would vote to give one HouseGuest a special power each week; this power was selecting the third nomination each week.