The present research investigates the influence of individual differences in the strength of stereotypic associations on category-based and individuating impression formation. In Experiments la and 1b, a target's category membership affected the ascription of stereotypical traits only when perceivers had strong stereotypic associations (measured with an Implicit Association Test, Greenwald, McGhee, & Schwartz, 1998). For perceivers with weak associations, in contrast, impressions varied only as a function of individuating information. Employing a multinomial model for the "Who said what?" paradigm (Klauer & Wegener, 1998), Experiment 2 demonstrated that these effects are due to increased stereotyping and decreased individuation for perceivers with strong stereotypic associations, rather than to individual differences in the likelihood of social categorization. Implications for the relations between categorization, stereotyping, and individuation are discussed. (C) 2002 Elsevier Science (USA). All rights reserved.