With the goal of developing culturally appropriate approaches for assessing and supporting children's language use, teachers of 4-to 6-year-old children in northern Canadian rural and Indigenous communities are involved in a 6-year collaborative action research project. Teachers video record children's interactions during dramatic and construction play and then meet with university researchers to carry out inductive analyses of ways in which children use language to achieve social purposes. From these analyses, a Play-based Communication Assessment has been created. Examples from two teachers' classrooms in one Indigenous community are used to show how play contexts and the still-evolving play-based communication assessment provide opportunities for teachers to recognise and build upon the linguistic and cultural resources that children bring to classrooms. Through the play-based assessment and action research processes, teachers have come to recognise the richness of children's language when they are engaged in play and have gained understandings of their community's culture. Teachers and researchers are exploring ways to capture children's non-verbal communication abilities through this assessment approach.