Society has become more complex in recent decades, and this has increased the demands placed on the educational system and the teaching profession. This study focuses on the development and validation of an instrument that measures the basic skills of beginning teachers. The instrument was developed according to scientific knowledge on teacher skills and their legal context as described by the Flemish government. Teacher competencies are measured along three aspects: "behaviour," "capability" and "beliefs." Construct validation took place in two rounds, using data obtained from a survey of beginning secondary teachers that was conducted in September 2008 and June 2009. Exploratory factor analyses with oblique rotation resulted in 12 reliable scales, containing a total of 60 items. The instrument can be used in teacher-training institutes to explore the basic skills of graduating students. It can also be used in schools to initiate a process of reflection amongst beginning teachers and to adapt the induction programme to the needs of each beginning teacher. (Contains 7 tables.)