Involving students in the process of negotiating what and how to learn is a creative and innovative way of curriculum development, but rarely put into practice. Involving students in developing their own curriculum is way to challenge young people to use existing knowledge and life experiences, raise relevant questions to be addressed, and exercise participation rights. This process results in more democratic curricula that are better in tune with the contexts of the student body and the diversity it contains, as well as with children’s rights. This paper presents the results of a study involving twelve classes of three secondary schools in the Netherlands. Research questions include the development and evaluation of an instrument for students; the contribution that students make to the quality of curricula; and in what way student participation adds to the development of citizenship and 21st century skills and attitudes. Three instruments are used: an interview template for teachers based on ten aspects of the curriculum; a student worksheet with a coding scheme for analysis; and a student questionnaire on the usability of the worksheet as well as on their perception of voice in school and how they value having a voice and rights.