Approximately 78% of American adults do not engage in enough physical activity, which is problematic because physical activity is positively correlated with beneficial health outcomes. Contingency management (CM) interventions have been shown to produce clinically significant behavior change across a range of target behaviors and populations, including physical activity. Both prize‐based and deposit‐contract CM interventions work well and decrease the costs associated with intervention, but they can decrease the magnitude of potential payouts. The current study used a prize‐based CM intervention combined with a deposit contract in which each participant deposited money that was pooled in the prize system for all participants. This increased the potential magnitude of reinforcement while keeping costs low for each participant. Four obese and two healthy weight adults participated in the CM intervention, which was introduced according to a single‐case reversal design. Overall, participants took more steps during intervention than during baseline, with four participants regularly taking 10,000 or more steps during intervention.