This article presents findings of research into the quality control (QC) of schools from 2001-2006. In 2001 several targets for QC were set and the progress of 939 primary schools is presented. Furthermore, using cluster analysis, schools are classified into four QC-types that differ in their focus on school (self) evaluation and school improvement. Accordingly, the progress of those four types of quality control from 2001 to 2006 is shown. Next, regression analyses have been conducted to find predictors of school progress in QC. Finally, attitudes of schools towards external quality control will be discussed. (Contains 4 figures and 4 tables.)