Factors influencing participation in an employee fitness program have been studied in a group of 535 early recruits for a Health Fitness Center established at the headquarters office of a larger corporation. The overall participation rate (20% of eligible staff with convenient access to the facility) was much as in previous reports. Interest was relatively equal in men and in women. Typical recruits were middle-aged non-smokers who had previously been active elsewhere. Men had an above average maximum oxygen intake and muscle strength, but were also somewhat overweight and fat. Women were closer to their actuarial ideal weight, but had relatively lower levels of cardiorespiratory and muscular fitness than the men. Program acceptability factors (traveling time, hours of work, and cost) had little effect on participation. Subjects perceived that they were active for health, fitness, competition (men), and appearance (women). General and specific health beliefs were well-developed, but bore surprisingly little relationship to health practices and outcomes. It is thus argued that the shaping of attitudes by trial of an exercise program may be a more effective tactic for increasing exercise participation than general campaigns designed to change attitudes and values.