Bowen Family Systems Theory's central construct, differentiation of self (DoS), is one of the most recognized constructs to systemic researchers and psychology professionals. The present study reviewed the available evidence on DoS from the inception of the construct until July 31, 2020. A scoping review was conducted and a total of 295 primary studies were eligible for inclusion. Literature was categorized according to the hypotheses postulated by Bowen regarding: the associations between DoS and psychological and health outcomes and how DoS stability and similarity in partner levels operate within family systems. Descriptive data regarding studies on the measurement of DoS and in the area of psychotherapy were also compiled. Results revealed that there is ample support for DoS as a predictor of psychological health and marital quality, and that there are positive associations between DoS and better physical health and intergenerational relationships. Results of this review show that there continue to be underexplored hypotheses and a paucity of longitudinal or causal research designs to test the stability of DoS, the intergenerational transmission of DoS, and the efficacy of clinical interventions in modifying DoS to promote optimal well-being. Recommendations and next steps for researchers and practitioners are outlined.