Injection laryngoplasty as used in this chapter is synonymous with the term injection augmentation. Injection augmentation is a technique designed to enhance glottic closure in patients with glottic insufficiency, or failure of glottic closure, by injecting material into the lateral aspect of the vocal fold to move the vibrating surface to the midline. This type of injection augments the vocal fold and improves glottic closure. Injection augmentation originated over 100 years ago. However, the current indications, techniques, and materials have changed significantly. Paralysis, defined as loss of function due to neu-rological injury, remains a common cause of glottic insufficiency. In cases of paralysis, nerve function to adduct the vocal folds for voice production and coughing is interrupted, bilaterally or unilaterally, and the glottis becomes insufficient. While unilateral vocal fold paralysis remains the most common indication for vocal fold injection augmentation, due to the development of newer injectable materials and less invasive injectable techniques, surgeons routinely perform injection augmentation for glottic insufficiency due to other causes such as vocal fold paresis, vocal fold atrophy, presbylarynx, vocal fold scar, and soft tissue loss. Additionally, there is an increasing performance of vocal fold injection in the awake patient. This allows for immediate feedback and reduced anesthetic risk. Outcomes assessment for injection augmentation remains varied by lack of consensus and large-scale studies to identify the factors most instrumental in documenting optimal results. We review the history of injection laryngoplasty, the indications for injection, choice of injectate, outcomes, complications, and future directions of injection laryngoplasty for augmentation.