During the socialization process, one of the primary questions newcomers face is whether the job or the place really fits them. As they seek answers during this adjustment period, their perceptions of person-environment fit may evolve and change. In this paper, we aim to investigate how newcomers’ person-job fit changes during the socialization process, focusing on both the antecedents and consequences of such person-job fit dynamics. We collected data in four waves from 153 newcomers during their first year of entry. Our findings indicate that both needs-supplies fit and demands-abilities fit increase over this period. However, negative affectivity influences the growth rate of needs-supplies fit, decelerating its increase, while the growth rate of demands-abilities fit remains unaffected by negative affectivity. Additionally, faster improvements in needs-supplies fit and demands-abilities fit, correlate with higher job satisfaction and lower turnover intention. The paper further discusses both the theoretical and practical implications of these findings.