Although studies reveal that acquiring knowledge about a new workplace during organizational socialization leads to better integration, the pathway through which this occurs is not well understood. Previous research has explored the psychological contract as an outcome of socialization. This study explores its role within the socialization process. A total of 161 organizational newcomers undertook surveys at months one and three of tenure, with data used to test a model within which four psychological contract dimensions mediate the relationship between knowledge acquisition and employee outcomes. At month one, organizational and employee promise strength mediated the relationship between knowledge and outcomes. At month three, organizational and employee promise fulfilment mediated this relationship. Findings confirm the role of the psychological contract in the socialization process and suggest that effective integration requires extensive knowledge provision and active employee knowledge acquisition.