The 4-H Youth Development Program (4-H) teaches life skills. An understanding of the factors that drive participation in the California 4-H program can help the organization target its efforts to increase enrollment and benefit more California youth as they move toward adulthood. 4-H has long been associated with market-animal projects, but the effect of these projects on enrollment is not known. In this study, 7 years' worth of enrollment data from 27 Northern California counties was evaluated with linear modeling techniques to determine the impact of market-animal projects (beef, sheep and swine) on program participation. The analysis demonstrated that market-animal projects produce significant, positive effects on enrollment. Each beef project contributed nearly four new members to county enrollment; a single sheep project yielded just over two new members; and two new swine projects produced a single new enrollment. Region and population density influenced membership but year within the study period did not. These results demonstrate the multiplicative effect of beef and sheep projects on county 4-H enrollment.