This chapter discusses the outcomes of pan-European collaboration to support teachers in adopting inquiry based science education (IBSE) and in assessing their student’s inquiry skills and competences in classroom practice. The project team involved science teacher educators and second level science teachers from across twelve European countries - Belgium, Denmark, Germany, Greece, Hungary, Ireland, Poland, Portugal, Slovakia, Sweden, Turkey, United Kingdom. This project, Strategies for Assessment of Inquiry Learning in Science (SAILS), was funded under the EU Framework Seven programme (2012-2015). Through sustained collaboration between science teachers and educators and across borders, both classrooms and countries, a variety of teaching and assessment strategies that facilitate inquiry learning in the classroom have been highlighted. Teachers from across a diverse range of educational and cultural contexts have been supported to develop their confidence and competence in adopting inquiry and assessment of inquiry learning in classroom practice.