Policy and interventions should be informed by the best available evidence, but evaluations are not always optimally designed to inform decisions about policies and interventions in new contexts. Learning the most possible from evaluations is important; evaluating is expensive and policy makers should be confident about their decisions. Using evidence from previous studies can lead to better policy decisions, but there have been cases where doing so has led to interventions that have not worked. Learning from evaluations for decisions elsewhere has generally been more successful for interventions that are simple and are less context dependent (or context-dependent in a simple way, such as depending on the severity of the problem). With increasing focus on complex, context-dependent interventions, we need to ensure that evaluations can offer as much information as possible to guide decisions in other contexts