This study examines job involvement and work engagement as predictors of affective commitment. Specifically, we test the proposal of Hallberg and Schaufeli (2006) that work engagement is a mediator of the relationship between job involvement and affective commitment using a survey of 405 Italian working adults. To test the model, mediation effects technique and structural equation modelling were applied to the collected data. Our hypothesis that work engagement fully mediates the relationship between job involvement and affective commitment was supported. This is the first study to demonstrate the importance of job involvement in promoting affective commitment via three dimensions of work engagement. We therefore assert that HR managers should direct their available resources to promoting job involvement and work engagement in their employees.