Ergonomists play an important role in preventing and controlling work-related injuries and illnesses, yet little is known about the decision-making processes that lead to their recommendations. This study (1) generated a data-grounded conceptual framework, based on schema theory, for ergonomic decision-making by experienced practitioners in the USA and (2) assessed the adequacy of that framework for describing the decision-making of ergonomics practitioners from backgrounds in industrial engineering (IE) and physical therapy (PT). A combination of qualitative and quantitative analyses, within and across 54 decision-making situations derived from in-depth interviews with 21 practitioners, indicated that a single framework adequately describes the decision-making of experienced practitioners from these backgrounds. Results indicate that demands of the practitioner environment and practitioner factors such as personality more strongly influence the decision-making of experienced ergonomics practitioners than does practitioner background in IE or PT.