Regional cooperation in Southeast Europe started as an externally driven initiative, dominated by security concerns in the 1990s, but has now been locally appropriated. When considered an integral part of the EU and NATO agenda in the region, these externally started initiatives that were appropriated by local actors have delivered significant results in regional cooperation, for example in justice and security affairs. On the other hand, the early logic and structuring of regional cooperation has neglected the economy, energy and infrastructure, and social development. Thus, regional cooperation in these core policy areas is lagging behind. Even though regional cooperation between governments is dominant and expanding, leading to a multitude of local and top-down initiatives, for example in parliamentary cooperation, the results still do not match the announced high expectations. Greater political will and more commitment would be beneficial to sustaining and deepening local top-down initiatives and to increasing their capacities.