In almost all European countries, many schools offer a form of bilingual education provision according to which content subjects are taught either through two different languages or through one foreign language. This approach is known as Content and Language Integrated Learning (CLIL). The main problem addressed in this research article is the need to examine and describe the contribution of CLIL methodology to the development of bilingual language competence of students of a secondary vocational school. In addition, the study looks at the teaching and learning within a bilingual Slovak-English study program of the school, specifically at the implementation of CLIL methodology in content subjects taught within the program. Specifically, the extent, approaches, materials used in the study program to enhance bilingualism at school in general and the bilingual language competence of the students through CLIL methodology in particular, as well as opinions and perceptions of teachers and students were investigated. Three data collection tools were used -- interviews with teachers and students, classroom observations and document review. The results of the study indicate that various factors inside and outside the classroom and school enhance students' bilingual language competence with CLIL methodology playing an important but not a decisive role.