Scholarly interest in workaholism has increased dramatically in recent years. This research has underscored the detrimental effects of workaholism for employees, their families, and the organizations that employ them. Despite drastic improvements in the quality of studies examining workaholism over the past several decades, researchers continue to almost exclusively rely on older measures of workaholism or new measures derived from these original measures. In the present study, we outline why a new measure is needed and propose a multidimensional conceptualization of workaholism that encompasses motivational, cognitive, emotional, and behavioral dimensions. We then develop and validate a new multidimensional measure of workaholism: the Multidimensional Workaholism Scale (MWS). Evidence from 5 samples representing individuals working in a wide variety of occupations and industries throughout the United States (total N = 1,252) provides support that (a) our proposed 4-factor structure replicates and fits better than alternative models; (b) the measure demonstrates high reliability and content validity; (c) the measure demonstrates evidence for convergent and discriminant validity with constructs in workaholism's nomological network; (d) the measure demonstrates incremental validity in the prediction of important outcomes over and above prior measures of workaholism; and (e) the different dimensions demonstrate incremental validity in the prediction of specific outcomes over and above other dimensions of the MWS. Overall, results from the present study suggest that the MWS is a reliable and valid measure that can advance a more nuanced approach to research and practice relating to workaholism. (PsycInfo Database Record (c) 2020 APA, all rights reserved).