In a study combining methodological elements from cognitive psychology and social anthropology, we worked with professional contemporary dancers making choreographic movement material to investigate the effects of working with others during improvisation. Dancers improvised alone, in pairs, and in a trio, they self-reported the number of new movement ideas created within two and four minutes, and self-rated ease, interest, originality, and clarity. Within two minutes, higher ratings were assigned in the unfamiliar pair than the familiar pair condition but there was no effect of group size on the number of ideas created. Within four minutes, more ideas were created in the solo condition than the pair condition with no effect of group size on ratings. Open-ended responses suggested that the quality and relevance of the ideas increased in the duo and the trio conditions. The conclusions point to emergent aspects of relations between persons as fundamental to creativity.