
In the third season of Big Brother, which aired thirty-two episodes during the summer of 2002 from July 10 to September 25, a new twist was added to the game, in that the houseguests could compete for a Power of Veto. At a weekly meeting, the winner could decide to veto a houseguest that the Head of Household had placed on the nomination block. In this season, it was not possible for a nominee to use the veto on themselves.


Lisa was one of 12 contestants on Big Brother 3 who competed with each other to last the longest in a house together, as one contestant was voted out each week by their fellow contestants. Lisa was criticized by many houseguests after the competition as someone who was aimless when it came to strategy, but she chose to make her alliances publicly known toward the middle of the competition, when she broke away from former friend-in-the-house Chiara Berti, who talked about Lisa behind her back. She also chose to vote Amy Crews back into the house in a group vote over Eric Ouellette, with whom she had had an alliance earlier in the game.
Aligning with Danielle Reyes, who was less popular than her, and covertly campaigning to vote out Chiara and Josh Feinberg, Lisa eventually succeeded in being one of the final two houseguests that season, with Danielle. Lisa received $500,000 for winning the competition (with Danielle receiving $50,000).