“Initial impressions” bring together personality and social psychology like no other field of study—“personality” because (1) impressions are about personalities, and (2) perceivers’ personalities affect these impressions; and “social” because (3) social cognitive processes of impression formation, and (4) sociocultural contexts have major effects on impressions. To make these points, we first review how people explicitly describe others: the terms we use, how these descriptions reveal our theories about others, the important roles of traits and types (including stereotypes) in these descriptions, and other prominent frameworks (e.g., narratives and social roles). Then we highlight recent research on the social cognitive processes underlying these descriptions: automatic and controlled attention, the many effects of primes (semantic and affective) and their dependence on contexts, the acquisition of valence, spontaneous inferences about others, and the interplay of automatic and control processes. Third, we examine how accurate initial impressions are, and what accuracy means, as well as deception and motivated biases and distortions. Fourth, we review recent research on effects of target features, perceiver features, and relations between targets and perceivers. Finally, we look at frameworks for understanding explanations, as distinct from descriptions: attribution theory, theory of mind, and simulation theory.