Objectives: Previous general population survey research has found that, relative to monetary incentives, altruistic appeals are ineffective in increasing survey response and that offering additional monetary incentives is always desirable. We consider an alternative population—a pro-social population—and ask whether these same conclusions apply. Methods: To evaluate the relative effectiveness of different incentive strategies, we randomly assign individuals to one of five conditions. We consider altruistic incentives (a narrative appeal or a charitable donation) and monetary incentives (three separate lotteries). Results: Among pro-social individuals, “less is more”: altruistic appeals are just as effective, if not more effective, than costly monetary incentives. Moreover, the simplest lottery structure (fewer large-payoff prizes) is the most cost effective of the lotteries. Conclusions: The target population of interest matters when designing survey incentive strategies. Moreover, increasing the incentives budget is not always beneficial.