The use of behavioral contracting in exercise programs has been shown to be effective in increasing the frequency of exercise activity and in reducing dropout rates. A study was undertaken to examine the impact of three cardiovascular risk factors (poor physical fitness, obesity, and smoking) on both client willingness to sign a behavioral contract to adopt an aerobic exercise program and on the outcome of such contract signing. Of 179 individuals asked to sign the exercise contract, 96 did so; 21.9% partially met the contract goal of at least three 20-minute aerobic sessions per week, 42.7% fully met their goal, and 35.4% did not meet the exercise goal. Smoking and weight risk were related to contract signing, but level of physical fitness was not. Body weight was the only risk factor related to contract success. Health locus of control subscales were not related to either contract signing or adherence, and attitudes toward exercise were only weakly related. The findings support the conclusions that overweight people are less likely to sign an exercise contract, and those who do sign such contracts are less likely to adhere to contract requirements; and that smokers are less likely to sign exercise contracts, but those who do are as successful as nonsmokers. Behavioral contracting appears to be a useful technique for facilitating adherence to exercise programs. (NB)