The development and initial validation of a client-rated measure of therapist cultural comfort (the Therapist Cultural Comfort Scale [TCCS]) is reported. The first phase of the study involved content validation of the initial pool of items via consultation with (a) focus groups of doctoral student therapists and (b) experts in the field of multicultural counseling and psychotherapy. A 56-item pool generated during this phase, together with instruments used to gauge convergent and incremental validity, were administered to a community adult sample of current psychotherapy clients (N = 889). Exploratory factor analysis suggested 2 subscales representing negative and positive indicators of therapist cultural comfort. Item response theory principles guided final selection of subscale items. Analyses suggested good factor stability and reliability of the 13-item TCCS as well as strong measurement invariance across racial/ethnic minority status and gender. Total and subscale scores related as expected with other measures of multicultural constructs (cultural humility, missed cultural opportunities, and multicultural competencies). Generally, TCCS total and subscale scores also predicted working alliance and treatment progress above and beyond the effects of therapist general comfort. There were few differences in clients' perceptions of therapist cultural comfort based on client demographic characteristics. Implications for research and practice are discussed. (PsycINFO Database Record (c) 2019 APA, all rights reserved).