This paper conceptualizes IT service management (ITSM) capability, a key competence of today's IT provider organizations, and presents a survey instrument to facilitate the measurement of an ITSM capability for research and practice. Based on the review of four existing ITSM maturity models (CMMI-SVC, COBIT 4.1, SPICE, ITIL v3), we first develop a multi-attributive scale to assess maturity on an ITSM process level. We then use this scale in a survey with 205 ITSM key informants who assessed IT provider organizations along a set of 26 established ITSM processes. Our exploratory factor analysis and measurement model assessment results support the validity of an operationali-zation of ITSM capability as a second-order construct formed by ITSM pro-cesses that form three dimensions: service planning, service transition, and ser-vice operation. The practical utility of our survey instrument and avenues for future research on ITSM capability are outlined.