This study evaluated health benefits of long-term participation in an employer-based wellness program, focusing on selected chronic disease risk factors. A repeated measures longitudinal time-series study was conducted of 8 years of existing prospectively collected annual data, including clinical measures of weight, blood pressure, cholesterol, and body fat percent. Participants were divided into their risk levels at baseline. Outcomes were compared to level of participation, for which annual points earned was a surrogate. Participants had lower increases in body mass index (BMI) than the general population had during the same time period. Greatest improvements in BMI, blood pressure, and cholesterol were seen in those at highest risk levels at baseline and in those whose physical activity increased over time. It was found that long-term participation in this program improved BMI, blood pressure, and cholesterol. Most benefits were found for those in high-risk groups. This program should recruit more employees in high health risk categories and emphasize retention and increased levels of participation.