Internationally, university teacher educators are responding to the requirement that preservice teachers (PSTs) need to be confident, operational users of a broad range of technologies, and that they can apply their technological pedagogical and content knowledge (TPACK). TPACK is a framework representing the complex interactions of teachers' technological content knowledge and technological pedagogical knowledge with their pedagogical content knowledge; the interaction of the three domains is believed to produce effective teaching with technology. The challenge is designing an instrument that can validly and reliably evaluate whether PSTs have this wide range of knowledge, and if not, what their learning needs are. This paper reports on the development and validation of a self-audit survey instrument that evaluated 296 PSTs' confidence to use technologies to support student learning. Using Rasch modelling techniques, construct validity was assessed for participant and item fit for 100 survey items organized within 10 components representing the construct "PST confidence to use technologies to support student learning." Rasch modelling indicated the need to remove 23 ill-fitting items, which resulted in the development of a 77-item survey with strong construct validity and reliability. Technologies educators and researchers are encouraged to use this validated survey as a PST self-audit instrument.