The collaboration of an orthodontist, speech-language pathologists, and orofacial myologists in the compilation of this special issue of the IJOM is a significant happening. It is symbolic of the recent history of multidisciplinary assessment and treatment of a group of disorders known collectively as "tongue thrust." Such collaborations may be surprising and possibly disappointing to a group of dentists and speech pathologists who met over a decade ago and developed a statement questioning the validity of the concept that the tongue affects the teeth. Despite the subsequent endorsements of that skepticism by three powerful professional organizations (the American Speech-Language-Hearing Association, the American Dental Association, and the American Association of Orthodontists) all of which published position papers upholding the "Joint Statement" of that 1974 committee, therapy for what came to be known as abnormal orofacial patterns of behavior persisted in most parts of the country under the rubric "myofunctional therapy."
A major purpose of this publication is to evaluate the legitimacy of the field of myofunctional therapy in light of research before and after 1974. A second purpose is to describe the scope of present evaluative and therapeutic procedures. A third is to make recommen­dations concerning future directions for research and clinical activities.