The purpose of this article is to discuss the role of religious education and ethics instruction in the development of worldviews in public education using empirical data. The research question of the article is: How is the contribution of RE and Ethics in the development of worldviews perceived among 9th grade students? The study is based on qualitative interview data (N = 37) gathered from Finnish 9th grade students of different religious and worldview backgrounds. The article will also describe three cases from that sample: from Islamic RE, Lutheran RE and Ethics instruction. The data was analyzed with qualitative content analysis. The results indicate that students' perceptions on the contribution of RE or ethics to the development of their worldviews could be divided into two groups: RE or Ethics were seen as contributors to students' already existing worldviews or considered insignificant in relation to the development of their worldviews. Whether the instruction was considered strengthening or irrelevant in the development of a worldview did not depend on the background of the student. Aspects related to experiences about the instruction were intertwined with the questions referring to the contribution of instruction in the formation of worldviews.