Newcomers rely heavily on incumbent team members to help them adjust to their new team environment. This incumbent-newcomer relationship has been studied extensively from the newcomer perspective, however few studies have considered the incumbent’s perspective regarding newcomer socialization to illuminate when and why individual incumbents engage in newcomer socialization. I examine how the incumbent’s attitude (goal commitment) and the newcomer’s role (newcomer role criticality) affect the extent to which incumbents share information with the newcomer, as well as the positive consequences that such behavior has for the incumbent. Using a sample of 182 incumbent-newcomer dyads nested in 62 teams, I find that engaging in information sharing has a positive effect on incumbents’ psychological need fulfillment and subsequent leadership self-efficacy. Contrary to my hypotheses, I find that goal commitment does not predict information sharing when controlling for task mastery. These findings contribute to the nascent research examining incumbents’ perspectives and experiences during newcomer socialization and demonstrate the unique incumbent-newcomer relationships that may develop within a team.