Sociocultural theory focuses on group processes through time, and argues that group phenomena cannot be reduced to explanation in terms of the mental states or actions of the participating individuals. This makes sociocultural theory particularly useful in the analysis of group creativity and group learning, because both group creativity and group learning emerge over time from the successive contributions of individual members, and they are difficult to reductively explain in terms of the mental states or actions of participating individuals. This paper presents a case study of group creativity, analyzing how a collective creative product emerges over 17 successive encounters of an improvisational theater group. This case study demonstrates the value of sociocultural theory in the study of group processes over time. And yet, it suggests that to fully explain group creativity and group learning, existing sociocultural theory must be extended beyond a narrow focus on process and practice, to focus on three levels of analysis: individual creative acts, interactional dynamics over time, and the emergence of collective group creations.