Disparities in chronic disease risk by occupation call for new approaches to health promotion. WellWorks-2 was a randomized, controlled study comparing the effectiveness of a health promotion/occupational health program (HP/OHS) with a standard intervention (HP). Interventions in both studies were based on the same theoretical foundations. Results from process evaluation revealed that a similar number of activities were offered in both conditions and that in the HP/OHS condition there were higher levels of worker participation using three measures: mean participation per activity (HP: 14.2% vs. HP/OHS: 21.2%), mean minutes of worker exposure to the intervention/site (HP: 14.9 vs. HP/OHS: 33.3), and overall mean participation per site (HP: 34.4% vs. HP/ OHS: 45.8%). There were a greater number of contacts with management (HP: 8.8 vs. HP/OHS: 24.9) in the HP/ OHS condition. Addressing occupational health may have contributed to higher levels of worker and management participation and smoking cessation among blue-collar workers. (Contains 1 figure and 3 tables.)