Using a four-wave longitudinal research design and a latent growth modeling approach, we modeled change in newcomers' perceived supervisor support and socialization outcomes (role clarity, work mastery, job satisfaction, and salary). Further, the role of perceived supervisor support in socialization outcomes was examined. The results showed that, on average, newcomers' perceived supervisor support declined during the period 6-21 months after organizational entry. The results showed further that the steeper the decline in perceived supervisor support, the greater the rate of decrease in role clarity and job satisfaction, and the slower the increase in salary over time.