1.1.2. Overqualification

Nowadays, overqualification is ubiquitous across European job markets, especially in Italy and Spain, and even more so among younger employees [25–27]. Beyond its ubiquity, overqualification raises concerns due to its negative effects on job satisfaction. For instance, studies conducted on young Spanish and Italian employees show that overqualified employees have lower job satisfaction [9,26,28].

Some scholars explain the negative effect of overqualification on job satisfaction based on equity theory. According to equity theory, employees compare the resources they put into work (such as level of education, skills, knowledge, experience) to what they receive in return (e.g., payment, recognition, or responsibility), in order to determine their sense of fairness [9]. When they perceive that their input is greater than what they receive, they develop a sense of unfairness, and as a result, they experience

dissatisfaction with their job. However, some studies have shown that, although overqualification has a negative relationship with job satisfaction, at the same time, it has a null or positive indirect relationship with mental health [10,26]. Therefore, we argue that overqualification might negatively affect employees' job satisfaction, but not necessarily their mental health. Furthermore, a study in German firms on the effects of overeducation on productivity, comparing employees working in jobs with similar levels of requirements, observed that overqualified employees are found to be healthier and strongly work- and career-minded [29]. Therefore, we also hypothesize that:
