Finnish teachers continue to receive significant attention among educators, educational leaders, and policy makers in the United States and around the globe. In addition, teacher collaboration continues to receive support as a meaningful part of teacher work and practice. Teacher collaboration is frequently described in various ways within different contexts. This study aims to: (a) better understand the nature of Finnish teacher collaboration by examining three teacher collaboration behaviors (sharing information and knowledge, planning, and problem-solving); (b) explore the extent to which Finnish teacher collaboration is formal (or school-required) collaboration and informal (or voluntary) collaboration; and (c) investigate the extent to which Finnish teachers attribute teacher learning to teacher collaboration. Using both qualitative and social network methods, the sample included 19 teachers from two comprehensive Finnish schools (1st–9th grades) who completed an online survey of professional network and open-ended questions. Analyses highlights the following: (a) Finnish teachers at a comprehensive school engage in the three teacher collaboration behaviors (sharing information and knowledge, planning, and problem-solving); (b) Finnish teachers at a comprehensive school value and collaborate in both formal and informal network structures; and (c) Finnish teachers at a comprehensive school attribute a degree of teacher learning, in terms of teacher improvement, to teacher collaboration.