This paper reviews and interprets recent demographic trends and prospe
cts in the two Irelands, North and South. We discuss both the influenc
e of religion on demographic behaviour, and the impact of demographic
trends on the distribution by religion. In the Republic of Ireland, we
show that the long-standing gap in marital fertility between Catholic
s and others had virtually disappeared by the 1980s. In Northern Irela
nd the gap is still there in the 1990s, though considerably reduced. H
owever, estimates of its size hinge on how the significant proportion
of non-respondents to the census question on religion are allocated. W
e identify some peculiarities of the non-respondent population which i
mply that it was more 'Catholic' in 1991 than first reports suggested.
The Catholic share of Northern Ireland's population may accordingly b
e larger -42 to 43 per cent - than previously thought. In both communi
ties, the future of the Catholic share depends less on fertility than
on migration patterns.