The purpose of this article is to demonstrate the value of a constraint-free study of occupation to occupational therapy. Constraint-free study refers to interdisciplinary scholarly inquiry that seeks to generate a deep understanding of how important occupations influence adaptation and health. Drawing on knowledge from animal behavior, anthropology, evolutionary biology, psychology, and primatology, primate play is discussed. Such knowledge enhances understanding of therapeutic play contexts and of play’s integrative impact on occupational performance. Moreover, a robust understanding of vital occupations, such as play, empowers practitioners, thereby reducing the profession’s vulnerability to external forces that diminish its economic and political position in the health care market. Precedents within and outside occupational therapy are described whereby control over the acquisition of basic knowledge has proven to be beneficial. It is concluded that both occupational therapy and occupational science will strongly benefit from their shared commitment to understanding the complexities of occupation.