The current study contributes to our understanding of workaholism as a negative construct, and to its measurement by examining the psychometric properties of a short 10-item workaholism scale called DUWAS (Dutch Work Addiction Scale). Confirmatory factor analyses were carried out in a heterogeneous sample of 2,714 employees from the Netherlands (n= 2,164) and Spain (n= 550). The results confirmed the expected two-factor structure of workaholism: working excessively and working compulsively. Moreover, multi-group analyses showed that this two-factor structure was invariant across both countries. Lastly, negative correlations among workaholism and psychosocial well-being (i.e., perceived health and happiness) are indicators of the negative nature of workaholism.