Abstract
By integrating the job demands-resources (JD-R) model with the proactivity literature, this study investigates the psychological mechanism and boundary condition that link work overload to helping behavior. We test our hypotheses using a four-wave, multi-source dataset from 366 employee-supervisor dyads in a manufacturing firm in China. The findings show that work overload is positively related to psychological strain, which in turn reduces helping behavior. Moreover, proactive personality functions as a critical personal resource; it buffers the detrimental effect of work overload on psychological strain, thereby weakening the indirect negative effect of work overload on helping behavior. These results contribute to the literature by uncovering the resource-depletion pathway between job demands and helping behavior, while highlighting proactive personality as an agentic, behavioral trait that drives employees to managing heavy workloads and sustain resource-sensitive helping behavior in demanding work environments.