This chapter takes a broader look at the use of verbal data in contemporary decision process research. We examine a range of approaches to the elicitation and analysis of verbal reports with the purposes of both describing decision processes and testing theories about them. We recommend and illustrate good practice, thereby providing researchers with the means to make good research design decisions. We define a decision process as a transformation of a structure over time. A decision maker’s mental representation of a decision problem is such a structure, one that includes both cognitive and affective components. Decision problems can be represented in many different ways. For example, decision alternatives can be represented either holistically, or by the attractiveness of different cues, or by arguments for or against the alternatives. Fundamental to process theories is the notion that mental representations can change from the beginning of a decision process until the decision is made, and can continue to change after the decision. These transformations of decision representations are brought about by processes, or operations, defined by a process model or theory, such as the elementary information processes (EIPs).