In the current study we replicated and extended the validation of the Multidimensional Workaholism Scale through: 1) the examination of the relationship between the MWS and the Bergen Work Addiction Scale; 2) the test of measurement invariance of the U.S. and the Italian versions; and 3) the analysis of predictive validity of the MWS through a series of cross-lagged panel models on a two-wave Italian sample (N = 304), including work-family conflict and emotional exhaustion. Configural, metric and partial scalar invariance was achieved on a sample of 591 Italian and 313 U.S. workers. Results supported convergent, discriminant, and predictive validity of the Italian version. Evidence of the predictive role of workaholism was found in relation to work-family conflict and emotional exhaustion. Finally, the different dimensions demonstrated some incremental validity in the prediction of specific outcomes over and above other dimensions of the MWS. In sum, we provided additional evidence of the validity of the MWS, which represents a tool for researchers and practitioners, validating its use in Italy to better understand the workaholism phenomenon.