This page gives links to the Library departments of councils in and close to the Highlands where you'll find lists of all their branches, many of which - especially in the larger towns - will hold local collections that can help with family history in their area. Local librarians are also likely to know local historians and genealogists who may be able to assist researchers.
Highland Council Libraries
Western Isles Council Libraries
Aberdeenshire & Banffshire Libraries
Aberdeen City Libraries
Perth & Kinross Libraries
Argyll & Bute Libraries
University Libraries usually contain useful collections of reference material - see Aberdeen University Library - and Local History & Genealogical Societies usually also have libraries that may be of great help, so see the pages listing them.