Across the world, countries have engaged in different iterations of curriculum change, and one of the common denominators of reform is the proposal of more agency for teachers around curriculum making. This is not an easy task for teachers. The purpose of this paper is to contribute to the discussion about the effects that international ERASMUS+ mobilities have had on the power of curricular agency of teachers from two European countries. This work is based on an empirical investigation of a qualitative nature which collected the testimonies of four school headmasters, a deputy principal and eleven teachers from Ireland and Portugal, teaching different curriculum matters, who were involved in the ERASMUS+ programme. Our findings evidence a very positive impact on secondary teachers' capacity to self-organize and achieve agency in relation to curriculum making by adapting their knowledge and skills, learnt through the mobility, to their own culture and context through collaborative communities of practice.