This chapter explores the principles of experimental research design as well as the issues and problems associated with different aspects of the approach. In particular, it considers the issue of internal and external validity, the common obstacles associated with experimental research, and what can be done to try and avoid or minimize them. The chapter first describes the five steps involved in the classic version of the experimental design before discussing three types of experimental design: laboratory experiments, field experiments, and natural experiments. It also examines the ethical issues that arise from experimental research and concludes by highlighting some of the advantages of experimental research.