This chapter focuses on the basic principles of research design. It first considers different types of research design, including experimental designs, cross-sectional and longitudinal designs, comparative designs, and historical research designs. It also discusses two types of research validity: internal validity and external validity. The chapter proceeds by describing various methods of data collection and the sort of data or evidence each provides, including questionnaires and surveys, interviewing and focus groups, ethnographic research, and discourse/content analysis. Finally, it examines six issues that must be taken into account to ensure ethical research: voluntary participation, informed consent, privacy, harm, exploitation, and consequences for future research.