A review of the literature which concentrates on Invitational Theory and Practice (ITP) has revealed an inconsistent and oft times confusing or contradictory use of named concepts, labels, phrases, wordings, definitions, and other such titles of major ITP principles (Shaw and Siegel, 2010). Presented in a glossary type format, the purpose of this article is to identify and define the basic tenents of Invitational Theory and Practice (ITP). Additionally, this glossary is proposed as the accepted standard for the various concepts and terminologies used to describe and or explain ITP in a consistent manner for application across a variety of disciplines and settings.