Human factors professionals are often involved in the design of new equipment and interfaces. Many design decisions have to be made, and the new design must be evaluated. Handbooks and articles may offer some help, but the design issues are often quite specific, and it is difficult to find published data that can be applied directly. The HFE professional may then undertake her own investigation. It can be a formal research study or it can be a quick collection of data to illuminate critical aspects of the research problem. This chapter gives an overview of common investigative methods in HFE.