This chapter analyzes what makes highly affective collaborations unique and how the complexity of such collaborations can be studied. Drawing on previous research, it explores in-depth innovative methodologies that are designed to capture the key elements of complexity during productive interactions. Components of these methods are then applied to two distinct settings: preschooler free play and early elementary playful learning. The qualitative analysis of free play focuses on how synchrony, intersubjectivity, and shared meaning emerge in a dialectical relationship to each other over the course of interaction and how the coding captures the vicissitudes of complexity. An adaptation of the coding scheme for preschoolers is provided for observational coding of teacher-facilitated early elementary interactions that measures both intersubjectivity and exploratory talk. The preliminary results indicate patterns in the coding of episodes that are consistent with the theoretical premise discussed previously.