Firms lose customers for various reasons all the time, raising the question of whether to stop marketing to these customers or to try to win them back through sending more marketing instruments. The answer lies in knowing the probability of regaining a lapsed customer. However, since customers have various reasons for dropping out, identifying which customers are worth reviving becomes important. This article examines this issue in a donation context, using data from a large not-for-profit organization. Results suggest that sending marketing communications with an appropriate frequency has a positive influence on reviving lapsed donors but sending overly frequent communications may evoke resistance to appeals. Furthermore, the varied behavioral histories and characteristics of lapsed donors affect the probability of revival. The article provides a useful approach to fundraising managers in a not-for-profit industry.