Scientists and conservationists increasingly rely on contributions by volunteers recruited from the wider public to work over large and ecologically meaningful spatial scales. Optimizing working in partnership with unpaid, volunteer citizen scientists and conservationists requires an understanding of the determinants of volunteer retention rates and how they are affected by management practices. To this effect, we present the novel use of the mark-recapture framework widely used in wildlife demography in order to quantify volunteer retention probabilities. We illustrate the versatility and power of the approach using a project that removed invasive American mink from 10,000 km2 in Scotland in partnership with volunteer citizen conservationists recruited from local communities. Wide scale adoption of the mark-recapture framework to analyze volunteer management will give novel insights into how volunteers interact with the conservation projects they are involved in and provide evidence for their optimal management.