High attrition often limits the efficacy of weight management programs, particularly those that serve primary care patients. We investigated stage of change and other predictors of retention in a behavioral intervention program that enrolled adult obese patients at three primary care sites. The program included practice improvements and provider training, as well as individual lifestyle counseling and educational group classes for participants. We analyzed predictors of whether participants returned for counseling visits and whether they attended group classes. The 461 participants were mainly women (84%) and minorities (87%), and most of them were in the preparation stage for dietary and physical activity changes. A total of 134 (29%) participants returned for at least one follow-up visit with their counselor and 85 (18%) attended at least one class. Baseline stage of change was not significantly associated with either return visits or class attendance (p = .875 and .182, respectively). Men and participants with children in the household were less likely to return for subsequent counseling sessions (p = .012 and .027, respectively). Age and employment were associated with class attendance (p = .099 and .034, respectively). Focus groups with participants confirmed that reasons for dropout included physical limitations or health issues, family issues, stress, and lack of social support. We conclude that prescreening of patients for readiness to participate and attention to personal barriers related to family and work might improve program retention. More frequent contacts between visits and stronger provider engagement might also strengthen the intervention.