This field study examined how early socialization experiences affect new employee mastery of socialization content and socialization outcomes. New employees reported the realism of their preentry knowledge and the helpfulness of socialization agents. A follow-up survey assessed mastery of socialization content along with role clarity, job satisfaction, and affective organizational commitment. The results, based on 194 new employees of a large educational institution and using structural equation modeling, were highly supportive of the hypotheses. Realism of preentry knowledge and agent helpfulness, the two indicators of early socialization experiences, were associated with greater role clarity, job satisfaction, and organizational commitment. In addition, the mastery of specific socialization content dimensions, the often-assumed intervening processes, was explicitly shown to mediate those relationships. The specific patterns of mediation observed further advance our understanding of the relationships between new employee mastery of socialization content and the determinants and consequences of that mastery.