This article focuses on antecedents in the evaluation of health programs and highlights the diversity of theories and methods applied to the field. In order to provide support for evaluative research in HIV/AIDS, the article discusses several classical principles in epidemiology, particularly the theory of causal inference and its limits for approaching infectious diseases. The article contends that recent debates concerning the logic and applicability of ecological studies establish convergent interests between epidemiology and evaluative research, concerned with incorporating contextual variables into the analytical models. The principles and typologies of contemporary evaluative research are explained with a view towards defending an analytical model for health-disease processes from the perspective of evaluating actions and programs. The article concludes by highlighting common proposals and convergent trends in epidemiology and evaluative research, serving as the framework for discussion on the limits and potentialities of the proposed model.