The paper is about cross-linguistic variation, in particular morphosyntactic variation, and the way linguistics deals with it. It is an attempt to answer the question whether linguistic systems, which may be different on the surface, also show variation at a deeper level. The first part of the paper discusses the results of linguistics, mainly formal linguistics, in the area of word order phenomena and related issues. The second part of the paper analyses data from several languages in support of syntactic variation at a deeper level and demonstrates that variation is a property of grammar at an underlying level. An approach which ignores this in favour of positing only a common set of principles shared by all languages makes the wrong predictions in the grammar of individual languages.