Environmental educators exchange ideas in social networks, which may in turn impact their practices. This study uses social network analysis, surveys, correlation analysis and interviews to examine the relationship between network and practice change in three professional development programs. In the first program that used face-to-face activities, educators' in-degree and betweenness centrality and in-degree tie strength were positively associated with practice change. In the second, online only program, only in-degree centrality was positively associated with practice change. However, in the third program with both face-to-face and online activities and the highest network density, no significant associations between network characteristics and practice change were measured. The results help us understand the role of developing professional networks in educators' practice change through professional development programs.