This article examines the possibilities and challenges in turning a top-down action research project led by high-level public authorities into a shared and collaborative, multi-site and multi-professional bottom-up action research project. For this purpose, the article explores the initial stages of a European level action research project called 'Linguistically Sensitive Teaching in All Classrooms' that aimed to help teacher education systems better acknowledge linguistically diverse student populations in seven European countries. The analysis of the data sought to identify how to promote linguistically sensitive initial teacher education by incorporating reflection tasks into existing courses, and how to transform a top-down research project into a shared and collaborative bottom-up action project. The primary data consisted of 19 video-recorded online research meetings. Qualitative analysis was used to identify 'critical moments' in the data; these included a moment of major insight where transformation of project related ideas took place. The findings showed that linguistically sensitive teaching as a phenomenon is complex and the related terminology challenging to translate between languages and contexts. Furthermore, a European level action research requires negotiating a joint understanding of the roles of the participants and the individual perceptions of project ownership in each context. This suggests that a deeper understanding of the processes of participation and the partnerships involved in the action research may be as valuable as the actual reflection tools developed in the project in securing a systematic change towards linguistically sensitive teacher education.