Cross-Sectoral Collaboration: Challenges and Opportunities of ‘Joint’ Action is an open-access report offering fresh insights into the governance of critical infrastructures. By blending perspectives from academia and industry, it explores how sectors such as energy and transport can collaborate across legal, organisational and technological boundaries in the era of digitalisation and the green transition. The report speaks directly to academics, policymakers and industry leaders. Its sections span diverse contexts, from crisis coordination in international emergencies to the role of artificial intelligence in energy networks, and from lessons learned from the Delta-Rhine Corridor initiative to analysing pressing challenges in infrastructure maintenance, the legal complexities of transitions, trust in digital transformation and the principles of good governance in collaborative networks. A central message is that collaboration requires more than good intentions. It demands deliberate governance choices, active trust-building and the integration of public values such as transparency, inclusivity and sustainability.