This article provides a comparative and longitudinal analysis of the policy selection methods adopted by Northern Ireland’s five main parties. Drawing on data from multiple sources, it sheds light on an important element of intra-party democracy and party organisation in the region. Accounting for instances of reform, this article reveals the extent to which the parties have altered their procedures following the introduction of devolved power-sharing in 1998. Policy development is revealed to be primarily top-down in nature, with a clear professionalisation of the process in recent times. In a concurrent development, parties have also adopted a more proactive and, typically, consultative approach to policy development, affording ordinary members greater opportunities to register their views. However, such consultation also privileges several actors outside the parties’ boundaries, a finding which raises questions concerning both their organisational integrity and the nature and meaning of conventional party membership in Northern Ireland.