Successful outcomes for youth with disabilities require collaboration within and beyond the school system. Collaboration ideally includes a range of professionals across school systems, service systems, and communities coming together as part of a "transition network" to support the transition process. Using a quantitative survey of 509 secondary special educators and 25 semi-structured interviews, this explanatory sequential mixed methods study (a) examined the characteristics of transition networks (i.e., the social networks of secondary special educators), (b) identified variables associated with larger networks, and (c) explored educators' interpretations of these associations. Quantitative analyses indicated that larger networks were associated with working at the high school level, supporting students with moderate/severe disabilities, increased years of experience, and greater knowledge about establishing collaborative partnerships. Interview analyses provided context for the quantitative results. These findings provide a deeper portrait of prevailing transition collaborations and have implications for educators charged with delivering high-quality transition programming.