This study examines why people initially give to charities, why they remain committed to the cause, and what factors attenuate these influences. Using an experimental design that links donations across distinct treatments separated in time, we present several results. For example, previous donors are more likely to give, and contribute more, than other donor types. Yet, how previous donors were acquired is critical: agents initially attracted by an economic mechanism are more likely to continue giving than agents attracted by a nonmechanism factor. From a methodological viewpoint, our study showcases the benefit of moving beyond an experimental design that focuses on short-run substitution effects.