Framed by the EU-project Hand in Hand focusing on Social, Emotional and Intercultural (SEI) competencies among students and school staff the paper discusses implementation and professional competencies based on a literature review. Five themes were identified: 1) Intercultural/transcultural competency is not often referred to in the same research as social-emotional learning, though socio-emotional aspects appear to be 'in the core', 2) it is crucial to be aware of agency among school staff in a SEI-implementation, 3) successful implementation is about more than the activities in the specific program, it is rather about elements in synergy and professional learning over time, 4) the subtle balance between adaptation and fidelity might best be addressed in an adaptive curriculum emphasizing active ingredients, and 5) this is a field with many intervention studies, but it is urgent to consider if the psychometric measures are sufficiently sensitive to catch the subtle changes related to SEI-competencies.