In this article we build on relational Sociometer Theory (Leary, 2005; Leary & Baumeister, 2000) to posit the impact of the belongingness threat of experienced incivility in one's work team on employee feelings of ostracism and subsequent engagement in proactive performance. Integrating the social-relational framework of Self-Identity Orientation Theory (Brewer & Gardner, 1996; Cooper & Thatcher, 2010), we nuance our predictions by hypothesizing that chronic self-identification orientations influence both the effect that experiencing incivility in one's work team exerts on feeling ostracized, and the impact that feeling ostracized has on subsequent employee proactive performance. Using a sample of 212 employees and their 51 supervising managers employed in an Internet service and solution company in China, we found support for our hypothesized model. Implications for theory and practice are discussed. (PsycINFO Database Record