 The study will randomize 200 sedentary community-dwelling adults with a suboptimal diet to 1 of 4 groups including: 1 increase healthy eating and activity; 2 decrease unhealthy eating and activity; 3 increase healthy eating and decrease unhealthy activity; and 4 decrease unhealthy eating and increase healthy physical activity. Subjects will self-monitor diet, physical activity, and mood via PDAs during a 2-week baseline period, a 3-week prescription period when payment is contingent upon changing eating and activity simultaneously to targeted standards, and a 4-month maintenance period. Targeted and collateral diet and activity changes will be measured by self report, accelerometer, and grocery receipts. Bogus pipeline urinary testing will encourage adherence. Laboratory testing will measure behavioral choices, craving, and attentional allocation to restricted foods and activities in a permissive context in order to shed light on behavioral and psychological processes that mediate healthy lifestyle change. Findings will help to fill an important gap in clinical knowledge about how to optimize healthy simultaneous change in diet and activity among adults. 