The goals of the current studies were to develop a measure of sexual orientation rejection sensitivity (RS) for sexual minority women (SMW) and to examine its preliminary reliability and validity. In Study 1a, data from 150 SMW were used to develop scenarios for the SMW Rejection Sensitivity Scale (SMW-RSS). In Study 1b, data from a second sample of 128 SMW were used to streamline the SMW-RSS and test its factor structure. In Study 2, data from a third sample of 300 SMW were used to test the convergent and discriminant validity of the SMW-RSS. The SMW-RSS demonstrated strong convergent validity, correlating with the indices of minority stress (discrimination, sexual identity acceptance concerns, difficulty developing a positive sexual identity, internalized negativity, and concealment motivation) and internalizing psychopathology (anxiety and depression symptoms). The measure also demonstrated strong discriminant validity, predicting psychosocial outcomes above and beyond existing measures of RS. Findings demonstrate the utility of the SMW-RSS to assess concerns and expectations of sexual orientation rejection among women and underscore the importance of examining the unique concerns about rejection that SMW experience. Additional online materials for this article are available to PWQ subscribers on PWQ’ s website at http://pwq.sagepub.com/supplemental