ABSTRACT Language has long been recognized as an important marker of ethnic identity. The identification is usually made in terms of some specific language or dialect, the use of which coincides more or less well with the boundaries of some particular ethnic group. This relationship obtains perfectly in present-day East Sutherland (Scotland), where the East Sutherland Gaelic mother tongue is almost the sole marker of fisherfolk ethnic identity. It can be shown, however, that this is only a very recent development and that the long-standing linguistic component of fisherfolk ethnicity is rather a lag in linguistic behavior vis-à-vis the rest of the population. The lag has taken four different forms over the past century or so, but the presence of such a lag is itself the actual ethnic marker. (Language and ethnicity, linguistic norms, language maintenance and shift; Scotland, Scottish Gaelic.)