The main objective of this dissertation was to test a model of mediation between meaningful work on the relations of personality traits with engagement and workaholism. To this end, two studies were carried out. In study 1, the objective was to evaluate if there was a constancy in the relationships between personality factors, meaningful work and engagement at work before and during the pandemic. The network analysis of the sample of 963 adults, with 828 respondents before the pandemic and 135 during the pandemic context, demonstrated that meaningful work not only acted as a mediator between the factors openness and conscientiousness, and engagement at work, but also demonstrated the consistency of the networks in the two samples, before and during the pandemic. In study two, the objective was to analyze whether the relationships of personality factors with work engagement and workaholism were mediated by meaningful work. This time, the results showed that the mediation of meaningful work in the relationship of the factors openness and conscientiousness with engagement at work was total. But in the case of mediation between neuroticism and engagement it was partial. Relationships of personality factors with workaholism were not mediated by meaningful work. The findings of this dissertation show the relevance of meaningful work as a factor that impacts the relationships of individuals personal characteristics with the levels of engagement and workaholism they experience.