Taking the Resources-Experiences-Demands Model (RED Model) by Salanova and colleagues as our starting point, we tested how work self-efficacy relates positively to negative (i.e., work overload and work-family conflict) and positive outcomes (i.e., job satisfaction and organizational commitment), through the mediating role of workaholism (health impairment process) and work engagement (motivational process). In a sample of 386 administrative staff from a Spanish University (65% women), Structural Equation Modeling provided full evidence for the research model. In addition, Multivariate Analyses of Variance showed that self-efficacy was only related positively to one of the two dimensions of workaholism, namely, working excessively. Finally, we discuss the theoretical and practical contributions in terms of the RED Model.