The three-volume handbook features descriptions of many techniques that psychologists and others have developed to help them pursue a shared understanding of why humans think, feel, and behave the way they do. At the broadest level, when choosing a method, researchers make decisions about what data or measurement techniques will best capture the thoughts, feelings, and behaviors that interest them; what research design best fits the question that they want to answer; and what strategies for data analysis best match the characteristics of their design and measurements. The simplest choice for organizing the presentation of material is the temporal sequence in which they will make these decisions. The earliest chapters in the handbook address the broadest questions related to research designs. These involve both (a) which research designs are most appropriate for which question; and (b) how to think about the ethicality and feasibility of the designs that address the question and the measures available. Next, handbook chapters describe the types of data that psychologists most often collect and how to determine whether the measurement techniques are the best ones for the research purpose. Later, the chapters return to issues of research design and present a panoply of options, further divided along more nuanced distinctions in their objectives. Chapters on techniques for data analysis follow, again with special attention to the fit between design, measurement, and analysis. Finally, issues and choices to be considered when writing up research to share with the community of psychologists are discussed in the handbook's concluding chapters.