Thirty-nine available family-group names are identified within the insect order Isoptera (termites). For all names the correct author, date, type genus, and combining stem are provided for the first time. This nomenclatural compilation is done to stabilize the usage of family- group names in the Isoptera in advance of a world catalog. Several problems of priority are identified and discussed. The little understood subfamily Foraminitermitinae is diagnosed; while generally believed by many authors to be a new, unnamed subfamily, it was in fact established by Holmgren nearly a century ago. The subfamilies Syntermitinae and Sphaerotermitinae are newly proposed for the mandibulate genera of nasute termites and for Sphaerotermes, respectively. The classification of Isoptera is briefly outlined.