The effectiveness of a pedometer intervention was affectedby manipulating the goals given to participants and byproviding social comparison feedback about how partici-pants’ performance compared with others. In study 1(n= 148), university staff members received a low,medium, or high walking goal (10%, 50%, or 100%increase over baseline walking). Participants walked1358 more steps per day (95% confidence interval [CI],729, 1985), when receiving a high goal than when receiv-ing a medium goal, but a medium goal did not increasewalking relative to a low goal (554 more steps; 95% CI,–71,1179). In study 2 (n= 64), participants received individual feedback only or individual plus social com-parison feedback. Participants walked 1120 more stepsper day (95% CI, 538, 1703) when receiving social compar-ison feedback than when receiving only individual feed-back. Goals and the performance of others act asreference points and influence the effect that pedometerfeedback has on walking behavior, illustrating the applica-bility of the principles of behavioral economics and socialpsychology to the design of health behavior interventions.