Summary: In both dictator and impunity games, one player, the dictator, divides a fixed amount of money between himself and one other, the recipient. Recent lab studies of these games have produced seemingly inconsistent results, reporting substantially divergent amounts of dictator giving. Also, one prominent explanation for some of these differences, the impact of experimenter observation, displayed weak explanatory power in a different but related lab game. Data from the new experiment reported here offers some explanations. We find that dictators determine how much they will give on the basis of the total money available for the entire experimental session, not on the basis of what is available per game. This explains the reported differences between impunity and dictator studies. When distributing a gift among several recipients, individual dictators show little tendency towards equal treatment. Also, we find no evidence for the experimenter observation effect. Comparison with earlier experiments suggests that differences in the context of the game, affected by differences in written directions and independent of experimenter observation, account for differences across dictator studies. We propose a hypothetical decision procedure, based on the notion that dictator giving originates with personal and social rules that effectively constrain self-interested behavior. The procedure provides a link between dictator behavior and a broader class of laboratory phenomena.