This article reports on collaborative action research in twelve northern rural and Indigenous communities in four Canadian provinces. Pre-kindergarten, kindergarten, grade one, and Aboriginal Head Start teachers worked with university researchers in three universities to create action research projects with the aim of supporting children's oral language and writing through play in their classrooms. Inductive analysis of focus group data shows that teachers gained understandings about play as a context both for supporting and for authentic assessment of young children's oral language. The building of trusting relationships, built through ongoing collaboration with colleagues within their schools and across four provinces, in addition to collaboration with university researchers over a number of years, was viewed as particularly influential to teachers' professional learning. Additionally, teachers talked about the value of opportunities to contribute to the development of teaching and assessment tools. Participating teachers came to see themselves as making valuable contributions to professional knowledge beyond their northern communities. The 4R's for conducting research in Indigenous contexts (reciprocity, respect, relevance, and responsibility) provide a framework for deriving implications from this collaborative research. It is important that the results of collaborative action research conducted in rural and Indigenous schools be widely disseminated to provide alternative perspectives to curriculum, research and practice that tend to be urban-oriented.