Rigorous evaluation of interventions is vital to advance the science of behavior change and identify effective interventions. Although randomized controlled trials (RCTs) are often considered the “gold standard”, other designs are also useful. Considerations when choosing intervention design are the research questions, the stage of evaluation, and different evaluation perspectives. Approaches to explore the utility of an intervention, include a focus on (1) efficacy; (2) “real-world” effectiveness; (3) how an intervention works to produce change; or (4) how the intervention interacts with context. Many evaluation designs are available: experimental, quasi-experimental, and nonexperimental. Each has strengths and limitations and choice of design should be driven by the research question. Choosing relevant outcomes is an important step in planning an evaluation. A typical approach is to identify one primary outcome and a narrow range of secondary outcomes. However, focus on one primary outcome means other important changes may be missed. A well-developed program theory helps identify a relevant outcomes. High-quality evaluation requires (1) involvement of relevant stakeholders; (2) evaluating and updating program theory; (3) consideration of the wider context; (4) addressing implementation issues; and (5) appropriate economics input. Addressing these can increase the quality, usefulness, and impact of behavior change interventions.