For several years, the European Commission has been investing in transnational mobility projects, namely Erasmus+, for the continuing professional development of teaching and non-teaching staff of schools for the sole purpose of improving the quality of education, as well as to establish networks of communications where teachers and schools can share their best practices and experiences. Although necessarily nestled in a proactive and positive school culture, these projects also have an impact on teachers professionally, but also on a personal level. This article therefore aims at studying how these international teacher professional development experiences change teachers’ biographies and their narrative expressions and possibly transform how they identify themselves personally, as European citizens, and professionally as European teachers. Empirical data collected through a multiple case study in Portugal appears to confirm that a considerable shift in professional and personal identity occurs through the participation of Erasmus+ KA1 projects for teacher professional development.