While European governance of individual policy sectors has received considerable academic scrutiny, less attention has been paid to the development of intersectoral coordination. This paper charts the emergence of a supranational boundary-spanning policy regime (BSPR) in education and employment in Europe. By looking at issues, ideas, interests and institutions, we gain a deeper understanding of the conditions for the emergence and further institutionalisation of European intersectoral coordination in education and employment from the 1990s onwards. The study relies on semi-structured interviews with European policy-makers in education and employment and EU policy documents. We analyse how endogenous and exogenous factors frame (policy) issues that contribute to the emergence and further strengthening of intersectoral coordination, the extent to which "ideas" for European education and employment stress intersectoral policy designs, how "interests" support or hinder intersectoral work, and which "institutions" are developed with an intersectoral reasoning. We find that endogenous forces (rather than exogenous ones) played a significant role in the emergence of a European BSPR in education and employment. Structural aspects and policy instruments ("institutions"), alongside "ideas" and "interests," then contribute to the institutionalisation of the European BSPR in education and employment.