This systematic review of the literature addresses the use of speech supplementation techniques for speakers with dysarthria and is part of the development of practice guidelines for the Academy of Neurologic Communication Disorders and Sciences (ANCDS). A search of electronic databases (PsychINFO, MEDLINE, and CINAHL) and hand searches of relevant edited books yielded 19 articles related to speech supplementation, a group of strategies that provide additional information to the speech signal to help communication partners understand unintelligible speech. Strategies include alphabet supplementation, in which the speaker indicates the first letter of the word spoken; topic supplementation, in which the speaker indicates the topic of the message; and gestures accompanying and illustrating speech. A review of this literature suggests that speech supplementation strategies may be useful for speakers with severe or profound dysarthria, regardless of medical diagnosis or type of dysarthria. Selection among the various strategies must be made on an individual basis because each strategy has unique advantages and disadvantages. Some strategies may have the benefit of improving speech production, especially in cases where rate reduction is an appropriate target for intervention. Listeners play a critical role in ensuring the successful use of strategies. Directions for future research are provided.