This article considers the theoretical and practical relationship betw
een core linguistics and sociolinguistics in relation to the emergence
of Principles and Parameters Theory. Parameters were introduced into
core Chomskyan linguistics in an effort to account for variation betwe
en languages. However, as we argue -and as has long been known in soci
olinguistics -languages (French, Italian etc.) are social rather than
abstract products. In this sense, core linguistics may need to pay mor
e attention than it has in the past to aspects of actual variation in
order to understand the limits and range of parameters. Thus we argue
that dialects of languages in themselves have parameters, and as such
may be defined within parametric limits. Here we believe there is some
thing of interest to sociolinguists, in terms both of structural defin
itions and of overall historical development. In general, then, while
variation has always been central to sociolinguistics, it is now centr
al, in one sense, to core linguistics; and here we have the opportunit
y to explore ways in which sociolinguistics and core linguistics may r
elate to each other in their interest in variation. (Parameters; varia
tion; dialect; Belfast; Ireland).