This study questions whether interpersonal strain at work (i.e., a measure of disengagement and withdrawal from others) is an outcome of burnout rather than a core facet of the syndrome by adopting the Burnout Assessment Tool (BAT) framework (Schaufeli et al., 2020). The BAT distinguishes between core (i.e., exhaustion, mental distance, emotional and cognitive impairment) and secondary symptoms. In doing so, the study conceptualizes a process in which individual differences in one's beliefs about nurturing and capitalizing from social relationships in the workplace (i.e., social self-efficacy) and the burnout symptom of emotional impairment (i.e., deterioration of self–regulatory control on negative emotions) operate in concert in determining interpersonal strain. To test our predictions, a two-wave study using a sample of 346 white collar workers from a government agency was designed. Results revealed that, among the core burnout symptoms, emotional impairment predicted unique variance in interpersonal strain at work after two years. Furthermore, social self–efficacy beliefs were associated with a significant decrease in emotional impairment, which, in turn, mediated the longitudinal relation between social self–efficacy and interpersonal strain. Theoretical and practical implications of our results, as well as the limitations of our study, are discussed.