To examine the theoretical and empirical implications of integrating the network and team literatures, we opened three different research lines. First, we argued that leader multiplex ties with their team members fulfilled important functions for team performance. In support of our hypotheses, analysis of data from 84 teams of a Spanish public service organization suggested that leaders’ centrality in their teams’ multiplex networks comprising both advice and friendship ties predicted longitudinal change in team performance, above and beyond members’ own multiplex ties. Beyond main effects, leader multiplex ties differentially interacted with members’ own network ties. We discussed theoretical implications with respect to leader social networks and team performance. Second, we adopted a social network perspective to examine the social underpinnings of intergroup effectiveness—the dyadic effectiveness with which pairs of teams perform collaboratively. We proposed that the interplay of social network ties within and between teams predicted intergroup effectiveness differentially depending on levels of resource interdependence between teams. In support of our hypothesis, results from temporally separated, different-source data of 48 pairs of service and administration teams suggested that the interaction of intrateam density and strong ties across teams predict managerial intergroup effectiveness ratings differentially for low versus high levels of resource-interdependence. We discussed theoretical implications with respect to dyadic team effectiveness, the performance benefits of social network ties, and the design of team-based work. Third, we adopted a multi-level, social network perspective to examine the importance of leaders’ management of upper echelon relationships in the organization for facilitating their employees’ creativity. We tested this idea with a sample of 214 employees working in 30 teams of a public technology and environmental services organization, followed by in-depth interviews with 7 senior managers. Results suggested that team leaders’ centrality in the idea generation and idea promotion networks among other team leaders, as well as their garnering of sponsorship support from senior management, affected their employees’ creativity in addition to employees’ own external network ties. Moreover, team leaders’ centrality in the peer leader idea generation and senior management sponsorship networks interacted with employees’ own external ties in different ways to predict creativity. We discussed theoretical implications with respect to social networks, employee creativity, and leadership.