In the 1990s the innovative Content and Language Integrated Learning (CLIL) approach was introduced in mainsteam education in the majority of European countries. Between 2007 and 2010 we collected data as part of a longitudinal study into the effects of CLIL as an innovative way of teaching English as a Foreign Language (EFL) in secondary education. The research investigates CLIL approaches in their early stages in four European countries, and the effects on learner affect and EFL performance. Moreover, in 2018 we undertook a systematic review of literature on similar research carried out in European mainstream primary and secondary schools over the past 20 years. In 2019 my dissertation - comprised of four articles - titled 'Content and Language Integrated Learning in English as a Foreign Language: a European Perspective' was published.