Retention of volunteers and participants is a critical concern for programs that rely on their manpower, but limited empirical research exists, especially on youth volunteers. This descriptive, cross-sectional quantitative study examined the influence of volunteer motivation, participation, and science project type on the retention of 4-H youth volunteers ages 12 to 19 years participating in science projects in 3 states. An instrument was created for this study that included both existing survey scales and researcher-developed items based on combined research from the citizen science, volunteer development, and youth development fields. The research revealed that consistency and engagement were correlated with the predictors of retention, but race was not. 4-H science programs have a significantly higher likelihood of retaining youth participants than 4-H citizen science programs. Suggestions for youth educators to develop retention strategies are discussed based on the findings and future research into youth volunteer engagement is proposed.