Researchers are becoming increasingly interested in how early experiences within the family are relevant to an individual’s behavior at work. Drawing on Bowlby’s attachment theory, the present study addresses this topic by examining the relationship between attachment in adulthood and job performance, and the mediating role of burnout in that relationship. We used data from two samples (201 Dutch employees and 178 Romanian working students) and structural equation modeling to test this mediation model and its possible invariance across both samples. The results showed that in both samples, attachment-related anxiety was positively related to burnout, which was in turn negatively related to job performance. Attachment-related avoidance was not significantly associated with burnout or performance. These results were similar in both samples, thus increasing their validity. The results suggest that childhood and early socialization experiences play a role in shaping the employee’s behavior and well-being at work. The study is one of the few examining attachment styles in relation to burnout and performance (download full article).