Organizations rarely invest in contingent employees, at least relative to the human resources efforts commonly afforded to permanent workers — but should they? Traditional social exchange theory suggests that motivation and loyalty should be difficult to cultivate in short-term, fixed-term relationships like contingent employment. However, a novel social exchange model (i.e., the anchoring model) suggests that socioemotional exchange relationships can develop quickly in response to highly salient “anchoring events.” We position employee onboarding as a positive anchoring event that can quickly and durably drive contingent workers’ socioemotional exchange in the form of work engagement, self-reported task performance, and intent to return to the employing organization. Specifically, we develop and test a temporally grounded process model based on the three proposed stages of the anchoring model. Our model was supported across two studies, an initial cross-sectional evaluation of the basic model within a heterogenous sample of contingent workers (n = 121), followed by a three-wave evaluation of the more detailed process model among an organizational sample of seasonal workers (n = 378). Findings provide evidence that the anchoring model, including the expanded framework developed here, explains contingent workers’ attitudinal and behavioral responses to human resources initiatives in a way that traditional organizational theories have not fully achieved. Finally, recommendations for effectively managing contingent workers, through onboarding as well as through other efforts such as training and development, are also discussed.