The purpose of the present experiments was to systematically replicate Step it UP! Game interventions with adults with disabilities. Participants were divided into two competing teams, and the team with the highest step count participated in a prize drawing. Experiment 1 (N = 9) evaluated the efficacy of an extended version of the Step it UP! Game that included additional and longer sessions. Experiment 2 (N = 8) evaluated the addition of contingent experimenter attention during the Step it UP! Game. Baseline, Step it UP! Game, and Step it UP! Game plus interaction sessions were evaluated in a multielement design. The Step it UP! Game was effective with additional and longer sessions, and all participants took more steps during Step it UP! Game sessions. Adding experimenter interaction to the Step it UP! Game did not increase the efficacy of the intervention.