The aim of this project was to compare characteristics and factors that distinguished those individuals (n = 101) who participated in a worksite wellness program from those who did not (n = 100). This project was unique in that the majority of subjects were bluecollar workers. Factor analysis of a 35-item questionnaire resulted in six factors: perceived benefits of health promotion behaviors, perceived physical barriers of health promotion, perceived self-efficacy for health promotion behaviors, perceived psychological barriers, situational components relating to convenience of the wellness facility, and the need for social support. Discriminant analysis revealed that self-efficacy was the most useful factor in distinguishing between the two groups. Participants identified more benefits and fewer barriers to health promotion activities. Nonparticipants were older, less educated, and tended to view their age, their perceived lack of fitness, and perceived poorer health status as deterrents to regular physical activity. Nonparticipants also identified shift work, working overtime, responsibilities at home, and distance from work as important barriers to health promotion activities. Self-efficacy factors appear to warrant further investigation in future attempts to explain health promotion behaviors in this high risk group.