Investigating the implementation and dissemination of evidence-based health-promotion programs to reach large numbers of diverse older adults is needed. The purpose of this study is to examine relationships between class size and session attendance and assess differences in intervention outcomes based on these community-based fall prevention program characteristics. Pre-post data were analyzed from 2,056 falls prevention program participants. PROC MIXED for repeated measures and ordinary least squares regressions were employed. Approximately 32% of participants enrolled in recommended class sizes (eight to 12 participants) and 76.4% of enrolled seniors attended more than five of eight sessions. Enrolling in smaller class sizes was associated with higher class attendance (X 2 =43.43, p<0.001). Recommended class sizes and those with 13-20 participants reported significant improvements in falls efficacy and physical activity. Perfect attendance was associated with improvements in falls efficacy (t=2.52, p<0.05) and activity limitation (t=−2.66, p<0.01). Findings can inform fall prevention program developers and lay leader deliverers about ideal class sizes relative to maximum intervention benefits and cost efficiency.