Political education in school is aimed at preparing adolescents for their role as citizens, which comprises political participation as well as political knowledge. While it is generally agreed that basic knowledge about politics is a prerequisite to participation, the specific link between knowledge and participation is left unclear in normative theories of democracy and didactic approaches of political education. A study with 1324 German ninth graders tries to clarify the relationship between the two constructs. The findings show a positive effect from knowledge to the expressed willingness to participate in politics in the future. But against the expectations, already performed political participation does not increase knowledge about politics. Furthermore, girls and pupils with migration background show less knowledge and express less willingness to participate.