Content and Language Integrated Learning (CLIL) approach has become one of the bilingual education pillars worldwide. Its application often relies on quality instruction; therefore, careful preparation of future CLIL educators will guarantee adequate CLIL implementation. Despite the extensive research on the method used since the 1990s, little is known about the competence-based training process of content and language teachers. Through a multi-dimensional perspective of the current research, including qualitative and quantitative methods, the study authors attempt to demonstrate that CLIL competences can be adequately developed. In our project, we taught a postgraduate course on Delivering the curriculum through English to 26 educators and analysed the development of their professional skills. Pilot study results show that competence development is highly correlated with linguistic awareness, in-depth theoretical and applied knowledge of the CLIL approach and mutual support within teaching community. Regardless of the fundamental idea of formative exploration, our study presents some findings deserving of thought by teacher trainers and policymakers currently applying CLIL methodology.