Stuttering is the interruption of normal flow of speech. It is characterized by frequent repetitions or prolongations of sounds or syllables, involuntary and irregular hesitation, broken words, and silent or audible blocking (Table 21–11). Stuttering typically begins between 2 and 7 years of age, with a peak onset at age 5 years. Stuttering must be distinguished from normal dysfluencies that occur frequently in young children but generally last less than 6 months. The onset is typically insidious, and the child is usually unaware. Anxiety commonly aggravates the disturbance. About two-thirds of individuals who stutter ultimately are able to make effective use of treatment techniques and overcome the difficulty. Some individuals recover spontaneously, typically before the age of 16 years.