Self-esteem is widely perceived to be important. This study examined the role of self-esteem as a moderator of social behavior in a sample selected to represent a broad range on the self-esteem dimension. Student subjects representing high, medium, and low levels of self-esteem were selected from a large sample (N=1,051) such that those characterized as low in self-esteem expressed negative self-attitudes. All subjects selected completed seven paper-and-pencil tasks measuring well-known and reliable psychological phenomena. Self-esteem was found to moderate three out of six phenomena that were replicated: (1) acceptance of more responsibility for desired than for undesired outcomes; (2) the false-consensus effect; and (3) unrealistic optimism concerning future life events. Attitude-consistency of cognitive responses to persuasion, primacy in impression formation, and beneffectance for social events were not moderated by self-esteem. No conclusions could be drawn about possible moderating effects of self-esteem on opinion change following counter-attitudinal role playing and attitude similarity/attraction. The results showed that when subjects with a wide range in self-esteem were tested, self-esteem was an important moderator of social behavior. (Author/ABL)