This chapter reviews research designed to inform assessment of early elementary collaborative learning. The various literatures focus on the following contexts for learning and development: classroom quality, parent–child interactions, and peer collaborations. Across these different relational contexts, certain key features that promote optimal development are identified. For example, assessments of classrooms that focus on teacher–student interactions that are attuned to the norms of children’s cultures and that promote student voice and personal connection to the curriculum are found to be highly relevant. In the parent–child interaction literature, microinteractions in which parents coregulate children’s affective and cognitive functioning influence positive child outcomes when the affective content is positive and the history of the parent–child relationship is one of sensitive responsiveness and shared goals. Within the peer collaboration literature, support for contingency, shared control, joint attention, and engagement are most crucial and can be provided by specific tools and materials, including technology. Language exchanges are most generative of new learning when there is support for exploratory talk embedded in the activity and/or supported by the teacher. These contexts vary in the extent to which they reflect traditional Western schooling versus the community participation models of learning in the majority world. The ideal context is one that is both widely culturally valid and generative for learning via collaboration.