This study examined the role of three personal resources (self-efficacy, organizational-based self-esteem, and optimism) in the Job Demands-Resources (JD-R) model. The authors hypothesized that personal resources (1) moderate the relationship between job demands and exhaustion, (2) mediate the relationship between job resources and work engagement, and (3) relate to how employees perceive their work environment and well-being. Hypotheses were tested among 714 Dutch employees. Results showed that personal resources did not offset the relationship between job demands and exhaustion. Instead, personal resources mediated the relationship between job resources and engagement/exhaustion and influenced the perception of job resources. The implications of these findings for the JD-R model are discussed.