The purpose of this chapter is to give the reader an overview of major research designs utilized within the field of health psychology. This chapter encourages researchers to consider the primary purpose of individual studies within a program of research and to consider designs that best match those purposes. The reader is assisted in thinking through foundational aspects of their research hypotheses to choose features of the study design to best address their questions and to best detect significant effects when they exist. In this way, overlap between design and statistical considerations are highlighted. Additional chapters focus on the choice of study measures and on behavioral medicine interventions in detail, so the discussion of these topics within this chapter is brief.