The effectiveness of any public health intervention is determined by its theoretical efficacy and by the level of engagement of the target population. A computer simulation model and basic epidemiologic concepts were used to estimate the effectiveness of interventions for preventing Lyme disease in a hypothetical community. The process for estimating numbers of Lyme disease cases prevented by each intervention is described. This assessment compares the effectiveness of alternative community-based prevention strategies, illuminates the limitations and distributive effects of interventions, and helps clarify available prevention options for community residents.