In recent years there has been increased interest in outcome-based social policy-making and management. The UK has been in the forefront of this movement but similar movements have been identified internationally. This interest in outcome-based decision-making has been given particular impetus through the ‘results’-based movement in evaluation and performance management since the 1980s, which has increased in scope over time, slowly changing its emphasis from cost reduction and measuring outputs to measuring outcomes. This change has been widely welcomed by policymakers, practitioners and academics. However, there is evidence that the reality is often rather less than the rhetoric. Moreover, the ‘attribution problem’ of attributing changes in outcomes to specific social policies has remained a major issue. The conceptual solution of constructing ‘cause-and-effect’ models, imported from the policy evaluation field, has only recently become common for operationalising these models. This article outlines the evolution of interest in outcome-based social policy-making up to recent times and the growing realization of the importance of the attribution problem. It then outlines both how the ‘cause-and-effect’ policy modelling approach can partially tackle the attribution problem, but also its inherent limitations. Lastly, the article uses several case studies in current UK social policy-making to demonstrate the potential importance of the reasoning embedded within cause-and-effect models but also the dangers in policy-making which adopts this approach without understanding its conceptual basis or in fields where it is inappropriate, given the current state of our knowledge of social policy systems.