The educational system in the Netherlands has a large private sector which is state-supported in the same manner as the public sector. I t consists mainly of denominational schools. In this article, a sequel to an article on primary education, the effects of school sector (public, Catholic, Protestant) on students' scholastic achievement are studied within two levels of secondary education. At both levels sector effects on key aspects of school success are found. These are generally small, but tend to cumulate in favour of one of the three sectors. Protestant school students perform best at the top level (VHMO), Catholic school students at the level of ULO. In neither case do public school students manage to do better than their counterparts in the private sector. These results suggest that differences in school sector effectiveness may partly explain the persistence of denominational education in the Netherlands. ; The educational system in the Netherlands has a large private sector which is state-supported in the same manner as the public sector. It consists mainly of denominational schools. In this article, a sequel to an article on primary education, the effects of school sector (public, Catholic, Protestant) on students' scholastic achievement are studied within two levels of secondary education. At both levels sector effects on key aspects of school success are found. These are generally small, but tend to cumulate in favour of one of the three sectors. Protestant school students perform best at the top level (VHMO), Catholic school students at the level of ULO. In neither case do public school students manage to do better than their counterparts in the private sector. These results suggest that differences in school sector effectiveness may partly explain the persistence of denominational education in the Netherlands.