The implementation of a bilingual teaching program requires a series of actions concerning methodological training and language support for both teachers and students. The Bilingual Education Program at Escuela Superior de Ingeniería (School of Engineering, University of Cádiz, Spain) was approved by the Board of the School in 2014 with the aim of developing English-Spanish CLIL-based bilingual curricula for the various Bachelor degrees offered. Amongst the measures taken to implement the program, teacher training has been a priority, with monitoring being an essential part. Monitoring sessions have now been carried out for more than six academic years and have a double objective: gathering the teachers’ perceptions and beliefs regarding their role as EMI teachers and providing them with feedback as to their practice through class observation in order to fine-tune future language development and methodology programs. The goal of this paper is to show that monitoring sessions may serve as a valid tool for assessing the impact of in-service training on bilingual teaching. The results show that teachers have experienced remarkable progress by incorporating language awareness into their practice as EMI teachers, thus contributing to improve the language level of both their students and themselves, and by applying specific didactic strategies to make the learning process more dynamic, participatory, stimulating and creative.