Much experimental (lab and field) and observational work has shown that people act more generously when they are observed and observe others in social settings. But the explanation for this is unclear. An individual may want to send a signal of her generosity in order to improve her own reputation. Alternately (or additionally) she may value the public good/charity itself and, believing that contribution levels are strategic complements, give more in order to influence others to give more. We perform the first series of laboratory experiments that can separately estimate the impact of these two social effects, and test whether influence is consistent with the desire to influence, and whether either of these are consistent with anticipated influence.