Whether motivated by reciprocity or conformity, imitation is common in public good contexts. We consider the incentive for an agent to contribute to a public good if he expects imitation from others. Using a sequential public good game with exogenous ordering, we show that agents early enough in the sequence who believe imitation to be sufficiently likely would want to contribute. By contributing, they expect total contributions to increase significantly. We also show that preferences determine how early an agent need be, that the observed share of imitators in experiments is sufficiently high to warrant contribution and that an increase in group size reduces the incentive to contribute.