This paper examines the social tie formation of 18 novice teachers in the United States. The authors use a novel interview technique to understand the relationships among organizational structure, individual agency, and experience in how early career teachers (ECTs) construct and maintain their social networks. This analysis yielded several interesting findings. First, ECTs formed moderately larger and more diverse groups of close colleagues over time. While organizational structure remained an important influence on ECT social network ties, ECTs exerted greater agency with experience as they began to seek resources outside their grade-level peer group. Second, ECTs used an increasingly diverse set of weak ties to secure resources for challenges they faced that extended beyond instructional matters (e.g., behavior, meeting diverse student needs). Third, while social networks became larger and more diverse, expansion and diversity had limits. ECTs learned early in their careers to establish bonds with some colleagues while simultaneously buffering from others.