Although religion has long played an influential role in the structuri
ng of electoral choice, the relationship between religious mobility an
d party preference has been almost totally ignored by both political s
cientists and sociologists of religion. Similarly, while much empirica
l research has focused on the effects of mobility on political behavio
ur all have restricted their analysis to the link between class mobili
ty and individual political preferences or vote. This paper examines t
he impact of religious mobility on party preferences within Northern I
reland. The results show that the association between political party
preference and religion is remarkably strong. There is a virtual absen
ce of inter-sectarian party preferences (Protestants supporting Nation
alist, and Catholics supporting Unionist, parties) and of inter-sectar
ian religious mobility. Because almost everyone in Northern Ireland wa
s raised as a Catholic or Protestant, this leads to very limited patte
rns of religious mobility. However, we find that mobility of Protestan
ts into the None, or religiously non-affiliated, group is associated w
ith increased support for the major non-sectarian party and for less e
xtreme sectarian party support. The implications of these findings for
a political settlement within Northern Ireland are discussed.