Five role delineation studies for health education specialists (HESs) were conducted from 1978 through 2015. The authors explored contributions and derived insights from these studies in advancing the profession of health education through professional preparation, credentialing, and professional development. The review process incorporated a comprehensive and methodic review of published and publicly available documents from the five studies: Role Delineation Project (1978-1981), Graduate Competencies Development Process (1992-1996), National Health Educator Competencies Update Project (1998-2004), National Health Education Job Analysis 2010 (2008-2009), and National Health Education Specialist Practice Analysis 2015 (2013-2014). The methodology involved identification and selection of resources; review of the published literature to identify comparison points that were analyzed across the five studies leading to data and information extraction; compilation of operational aspects, results, and professional buy-in; and identification of findings and eventually, themes. Three overarching themes emerged addressing: leadership, sponsors, and resources; a competency-based model of professional practice; and consistency and changes in defining the role of the HES. Nine major conclusions were drawn from the findings. Five key recommendations derived from the analyses and conclusions addressed greater health education role delineation research data set and report availability; wider dissemination of study findings and technical reports; increased representativeness of HES from key work settings and the three levels of professional practice in future role delineation studies; expansion of the research involvement and support from the full profession; and consistently naming the empirically based hierarchical model the Hierarchical Model of Professional Practice (HMPP).