Psychology, perhaps more than any other social science, has historically defined itself by the methodologies it employs in generating new knowledge. This chapter surveys the history of methodology in psychology. We begin by first defining the concept of a methodology, then survey early scientific methods of psychology with the work of Gustav Fechner in the 1860s. Fechner, along with other psychophycisists of the time, were of the first to promote a rigorous scientific method in the study and understanding of psychological phenomena. The quest for quantification in psychology would continue with the work of Francis Galton and his monumental discovery of empirical correlation almost thirty30 years later, which set the stage for a wealth of statistical methodologies that would arise in the early 20th twentieth century. These included the birth of psychometrics and testing, as well as the development of the factor analysis method used by Charles Spearman and others. By the early 1920s, geneticist R. A. Fisher revolutioned the application of quantitative methods by promoting null hypothesis significance testing, while simultaneously packaging experimental design into the method of the Aanalysis of Vvariance. We close the chapter with a survey of Sewall Wright’s method of path analysis, which, along with factor analysis (and the advancement of the computer), set the stage for the birth of structural equation models of the mid-to-late 20th twentieth century. While psychological science has been dominated by quantitative methods, the re-emergence of qualitative methods is also noteworthy. We conclude with a comment that psychological methods of the future, to be successful, will likely require a merger of both quantititative and qualitative approaches.