The conditions of formation of content-language integrated learning (CLIL) have been characterized with a number of theoretical and methodological factors, that have influenced the process of development from different perspectives. The origin of CLIL is connected with the prior methodological approach to second language acquisition – content based language instruction. It has been established with aim to reduce the gap in knowledge of English learners between spoken everyday English and Academic language. The reflection of the psycholinguistic views in CBI led to adoption of concepts of comprehensive output, input hypothesis and proximal zone of development in its subsidiary method (CLIL). Besides this, another methodology affecting formation of content-language integrated learning, known as “English for special purposes”, is also contextualized by specialty content, and they share common goals of learning. However, ESP keeps its focus on language, not content. The comparative analysis of CBI and ESP key features reveals the theoretical and methodological conditions of CLIL formation.
 The modified variations of CLIL approach, applied all over Europe like Bilingual Content Teaching, Bilingual Subject Teaching or Content-Based Language Teaching, relied on a common concept of learning a foreign language with a shift of focus from the language itself to the content expressed in this language. The bilingual model of education in European countries adopted the provisions of content-language integrated learning methods at the mainstream level in school education in France, Ireland, Finland, Estonia, Latvia, Poland, the Czech Republic, and it has been partially implemented within pilot projects in the UK, Spain, Germany, Italy and Sweden. The method was strongly supported by policy of the European Union and European Commission with an aim of promotion of language learning and linguistic diversity. The support of the European language policy and ideology was reflected in a number of projects launched in order to promote methods based on international cooperation, such as “Content and Language Integrated Learning in Germany” (CLILiG), as well as with the support of the Council of Europe “CLIL Quality Matrix” (2004) and the European Regional Action Scheme for the Mobility of University Students (ERASMUS).