Background: Current popular conceptualizations of the psychological process Repetitive Thought (RT) appear of limited accuracy due to construct confusion (i.e., equating RT with other similar constructs like rumination or worry), possible construct proliferation (i.e., naming the same construct twice), tautological definitions, and the construct being studied primarily in mentally disordered populations. This paper sought to unite current disparate lines of research surrounding RT, to illuminate and clarify the nature of RT.Methods: Two studies were completed: First, a systematic literature review was conducted to develop a more comprehensive and conceptually coherent model of RT. Second, the structural validity of the model produced by the first study was empirically tested using factor analytic and multiple regression techniques. Results: Exploratory factor analyses indicated an oblique three-factor model was empirically most appropriate, likely with a strong underlying general RT factor. Additional validation analyses confirmed the distinctiveness of the factors and their unique effects on health outcomes. A 36-item measure corresponding to this model is presented. Conclusions: This study contributes to our understanding of the nature of the broader concept of Repetitive Thought by clarifying its conceptual nature, refining the definition to be more in alignment with scientific principles, and demonstrating that an oblique three-factor model appears to best reflect the nature of the larger RT concept. The empirical and applied implications are discussed, and a 36-item measure is presented.