Although definitions of validity have evolved considerably since L. J. Cronbach and P. E. Meehl's classic (1955) review, contemporary validity research continues to emphasize correlational analyses assessing predictor-criterion relationships, with most outcome criteria being self-reports. The present article describes an alternative way of operationalizing validity--the process-focused (PF) model. The PF model conceptualizes validity as the degree to which respondents can be shown to engage in a predictable set of psychological processes during testing, with those processes dictated a priori by the nature of the instrument(s) used and the context in which testing takes place. In contrast to the traditional approach wherein correlational methods are used to quantify the relationship between test score and criterion, the PF model uses experimental methods to manipulate variables that moderate test score-criterion relationships, enabling researchers to draw more definitive conclusions regarding the impact of underlying psychological processes on test scores. By complementing outcome-based validity assessment with a process-driven approach, researchers will not only improve psychology's assessment procedures but also enhance their understanding of test bias and test score misuse by illuminating the intra- and interpersonal factors that lead to differential performance (and differential prediction) in different groups. (Contains 5 tables and 7 footnotes.)