Although instructional development for teachers has become an important topic in higher education, little is known about the impact it has on daily teaching practice. The lack of systematic programme evaluation is an ongoing concern. In this study we investigate by use of a quasi-experimental design, the impact of an instructional development program for beginning university teachers on their teaching approach. Quantitative pre-test as well as post-test data were assembled from 20 experimental teachers and 20 control teachers. At the post-test qualitative data were gathered too: 17 teachers of the experimental group and 12 teachers of the control group were interviewed. Paired "t"-tests and analysis of covariance with the pre-test scores as a covariate showed some effect of instructional development on teaching approach. The analysis of the qualitative data sustained this result. Our results reveal the influence of instructional development on teachers' teaching approach being slightly different for teachers belonging to distinct disciplines. Several interpretations and perspectives for further research are discussed.