This chapter overviews the research process from hypothesis generation to research design and data analysis. With emphasis on the latter, null hypothesis significance testing and effect size calculations are compared and a figure presented that can be used to help the reader to select the correct statistical test in specific scenarios. Common statistical analyses used in health behavior change research are described (meta-analysis, mediation, moderation, randomization checks, recruitment and attrition analyses, handling missing data and outliers). The chapter also describes process evaluation which provides useful information regarding implementation (what is delivered and how), mechanisms of action and the identification of contextual factors that influence the size of the intervention effects. The chapter ends by considering the RE-AIM framework that can be used to evaluate the extent to which an intervention has the potential to achieve public health benefits.