Tested implications for attribution processes of variation in the unit of perception in 2 experiments with college freshmen males (n = 20). In Exp I Ss viewed a 5-min videotaped behavior sequence. Ss were instructed to segment the behavior into as fine units of action or as gross units of action as were natural and meaningful to them. Results indicate that in comparison to gross-unit Ss, fine-unit Ss were more confident in their impressions, made more dispositional attributions, and tended to have more differentiated impressions. In Exp II Ss viewed either of 2 comparable sequences of problem-solving behavior; in 1, an unexpected action was inserted. Following the unexpected act, Ss employed more units of perception/min than controls who did not view it. It is concluded that the unit of perception varies according to situational constraints and that attribution theories assuming constant units are seriously in error. Implications of unit variation for the interpretation of attribution research are discussed. (17 ref) (PsycINFO Database Record (c) 2016 APA, all rights reserved)