This chapter discusses the necessity of designing our research projects to have an impact for end users and describes the five key research design principles central to the applied scientific method which high-quality research is recommended to adopt. These five principles are (a) the inclusion of reliable and valid measures; (b) the inclusion of sufficient and generalisable research samples; (c) the inclusion of the evidence of theoretical sophistication; (d) the inclusion of research designs that promote causal generalisations; and (e) the inclusion of research implications for end users. The chapter argues that the inclusion of these five principles maximises the opportunities of research to achieve an external impact and that this should be one of the key aims of conducting research at all levels. This chapter also discusses the process of research evaluation and the importance of planning this evaluation process within the research design stage.