Vladimir Prelog Science School is a well known institution offering good quality education through its general secondary grammar school programme. The school's primary interest is science and mathematics, and it offers the unique practical laboratory work in physics, biology and chemistry throughout all four years of the secondary education. In order to secure even better quality of education, we have decided to start teaching those subjects in English language. We have presented our project to the Croatian Ministry of Education and received their approval to implement bilingulal secundary grammar school programme. The school's goal is not only to start teaching the above mentioned subjects in English language, but to improve schooling and bring the spirit of internationalism. The biggest beneficiaries from the project would be our students, who will get the chance to take part in the programme that is unique in Croatia. All this will be done because the school aspires to implement standards in accordance with the general Strategy of education, science and technology as well as to achieve high EU standards of quality education and students' mobility. In order to meet this goal, teachers had to improve their general and subject related English language skills. The teachers came across various new subject related materials, which would then later be available to all the staff and students. Learning about other teaching traditions and ways in Europe was of great use to all the teachers since they were able to implement them in their own classes. Next objective was to produce more teachers who are able to manage projects. This was achieved by including all the teachers into all the project stages (from developing an idea to the evaluation stage) which led to increasment in every teacher’s confidence to manage a project of its own. This, together with improving the language competence, directly ensured their better position on the job market. We had four activities. The first activity consisted of two mobilities in Language School International, Cambridge, UK. The mobility part gathered overall ten teachers. Teachers improved their grammar and worked on their reading, listening and speaking skills and pronunciation in a controlled environment. They also got better at knowing subject related terminology. The second activity was a visit to a partner school - Redland Green School, Bristol, UK which was the base for both our job shadowing and teaching assignment. The plan was to study the way the school functions in general, the way projects are run there and how they are included in the curriculum. Also, we learnt about the school system in the UK, with special interest in development plan, teaching methods and similar. This resulted in improved language skills, skills needed for project management and teaching skills. The mobility gathered above mentioned ten teachers and the Headmaster. The third activity involved English language workshops organized for teachers of science and math by the English teachers from Vladimir Prelog Science School. This is the way teachers continually worked on developing and improving language skills. The workshop classes were also used for brainstorming in general, identifying the needs and phases of the project, task delegations, preparations for the trips, making of the lesson plans and similar activities. This all contributed to a good communication and flow of information between all the participants of the project. And finally, the fourth activity was ensuring the project's visibility which was directly affecting project competences of the teachers involved. The competences gained throughout the project were confirmed by both Croatian and European certificates such as: Europass CV, Passport, Europass mobility, Croatian Ministry of Education's approval, as well as Cambridge's FCE and CAE test. The experiences and information gained through this project were spread not only during the project, but also after its evaluation phase. Project has many goals so it is of utmost importance to spread the word about the results and the mobilities to as many people as possible. Teachers of the above mentioned subjects therefore improved not only their general English language listening, speaking and writing skills, but also very important subject related vocabulary which will enable them to teach in English themselves, while English language teachers became specialists for science and math related terms. Quality improvement together with internationalisation was also an important outcome. New and improved teaching methods as well as project management skills will surely lead to greater teachers' mobility. Through this mobility a greater tolerance of students and teachers towards other cultures is also likely to be achieved. Also, cooperation with the partner school was established and that opened the door to further projects.