This article outlines a set of methodological, theoretical, and other issues relating to the conduct of good outcome studies. The article begins by considering the contribution of evidence-based medicine to the methodology of outcome research. The lessons which can be applied in outcome studies in nonmedical settings are described. The article then examines the role of causal pathways between interventions and outcomes and especially the importance of delineating them in advance of undertaking investigations. The development of designs based on randomized controlled trials (RCTs) with fully articulated causal pathways is described. Ways of supplementing RCTs with methods to highlight elements in the causal pathway in outcome studies are indicated. The importance of adhering to best practice in reporting and analysis is also noted.