Background: Over the past decades, the issue of improving teaching in higher education has been seriously addressed. Centres for instructional development, aimed at enhancing teaching, have been set up in many countries. Instructional development for early career academics is perceived to be of particular importance. Given the considerable investments made, questions are raised with regard to the impact of instructional development. Purpose: This article gives an overview of four related studies into the impact of instructional development at one European University--the University of Antwerp. The study is prefaced with a conceptual framework and outline of theoretical motives. The results of the four studies are reviewed together and implications from the findings taken as a whole are identified. Programme description: At the University of Antwerp, early career academics have the opportunity to participate in an instructional development programme (140 hours of study, spread over 10 months). The programme aims to strengthen academics' competency-oriented teaching conceptions and to improve professional practice. The ultimate goal, however, is to achieve better student learning. Home assignments stimulate the transfer of what has been learned during the programme to practice. Sample: Over the four studies, quantitative as well as qualitative data were gathered from 40 early career academics and from more than 1000 students at the University of Antwerp. In the first three studies, the same academics and students participated: the teachers enrolled in the instructional development programme at the University of Antwerp in 2005, some of their colleagues not enrolled in the programme, and the students of all these teachers. In the fourth study, teachers enrolled in the programme in 2000-2001 were involved. In all studies participants came from different disciplines and volunteered to participate. Design and methods: In three of the four studies reviewed, data were gathered according to a quasi-experimental pre-test/post-test design. Twenty-three teachers who had enrolled in the instructional development programme at the University of Antwerp in 2005 were invited to take part (this was the experimental group). They nominated a colleague who was not enrolled in the programme, but whose teaching situation was otherwise comparable with their own, to serve as control teacher on a voluntary basis. The students taking the courses selected by the teachers were also involved in the research. Shortly before the start of the programme, questionnaires were distributed among the teachers and students. A post-test, using the same instruments, was conducted three months after the end of the programme. At that time, qualitative data were also gathered, by way of semi-structured interviews. In the first two studies analysis of covariance with the pre-test scores as a covariate was used to analyse the quantitative data. Two researchers independently analysed the interview data, using a semi-structured coding framework. In the third study, the student data used in study 2 was re-analysed using a multi-level approach. In study 4, long-term post-test data were gathered from an experimental group of 30 teachers, using a written survey with open questions. Results: Taken together, the results of the four studies reviewed indicate that the teaching "conceptions" of participants in the instructional development programme came more into line with the notions based on competency-oriented and student-centred education. However, there is nothing in the findings to confirm that the teaching "behaviour" of the participants comes more into line with this teaching concept, or that improved learning performances among students have been achieved. However, the results of the fourth study are encouraging with respect to the possibility of a long-term impact. Conclusions: It is suggested that the findings underline the need for an emphasis in instructional development on practical aspects of teaching. The policy of institutions should value participation in instructional development. Further, it is suggested that instructional development should not be restricted to novice teachers. (Contains 1 note, 2 tables, and 1 figure.)