This study examined the factor structure of a revised version of a measure of organizational citizenship behavior (OCB) and assessed its validity against an objective behavioral criterion. Ratings of employees' OCB were provided by managers of 16 restaurants in the fast service industry. The objective measure of behavior was whether or not employees returned an attitude survey. Factor analysis suggested that the revised OCB instrument adequately assesses two dimensions of OCB: altruism and conscientiousness. Further, as expected, survey respondents had higher mean levels of OCB than did nonrespondents. The results suggest that managers can perceive and assess subtle components of job performance with reasonable accuracy.