This chapter provides an account of the different methodologies that can be used to describe mother and infant interaction in nonhuman primates. Using my own experience as I evaluated these different methodologies and attempted to use them in my own research, I show how I realized that each methodology selects certain elements of this interaction as relevant. This entails that within each methodological design, researchers explicitly or implicitly answer several questions: First, what is interaction and which is the best way to describe the interaction among these units? Second, what are the mental contents (if any) of the individuals interacting? Each methodology focuses on different presuppositions leading to specific questions and leaving others aside. I will show how descriptions of the mother-infant interaction are shaped by implicit notions of communication and social interaction.