Networks and coalitions of stakeholders play a crucial role in the development and implementation of policies, with previous research highlighting that networks in tobacco control are characterised by an antagonism between supporters and opponents of comprehensive tobacco control policies. This UK-based study used quantitative and qualitative network analysis (drawing on 176 policy submissions and 32 interviews) to systematically map and analyse a network of actors involved in the development of European Union (EU) smoke-free policy. Policy debates were dominated by two coalitions of stakeholders with starkly opposing positions on the issue. One coalition, consisting primarily of health-related organisations, supported comprehensive EU smoke-free policy, whereas the other, led by tobacco manufacturers' organisations, opposed the policy initiative. The data suggest that, aided by strong political commitment of EU decision makers to develop smokefree policy, advocates supporting comprehensive EU policy were able to frame policy debates in ways which challenged the tobacco industry's legitimacy. They then benefited from the stark polarisation between the two coalitions. The paper provides empirical evidence of the division between two distinct coalitions in tobacco policy debates and draws attention to the complex processes of consensus-seeking, alliance-building and strategic action which are integral to the development of EU policy. Highlighting network polarisation and industry isolation as factors which seemed to increase tobacco control success, the study demonstrates the potential significance and value of FCTC article 5.3 for tobacco control policy-making.