Some theories of self-enhancement posit that very positive views of the self can disinhibit acting hostilely toward others, particularly in the context of provocation or negative feedback. Dynamics of this type was proposed as a function of individual differences in implicit egotism. Individual differences in implicit egotism were quantified on the basis of name-letter preferences, following which the same (N = 97) participants completed a daily life protocol for two consecutive weeks. Cross-level interactions revealed that the highest frequencies of hostile behavior were particular to participants high (relative to low) in implicit egotism on days of high provocation or negative feedback. The findings encourage greater attention to the potential interpersonal costs of high levels of implicit egotism.