Self-portrait of a woman who stutters
What is stuttering? Stuttering is a communication disorder in which the flow of speech is broken by repetitions (li-li-like this), prolongations (lllllike this), or abnormal stoppages (no sound) of sounds and syllables. There may also be unusual facial and body movements associated with the effort to speak. Stuttering is also referred to as stammering.
What causes stuttering? There are four factors most likely to contribute to the development of stuttering: genetics (approximately 60% of those who stutter have a family member who does also); child development (children with other speech and language problems or developmental delays are more likely to stutter); neurophysiology (recent neurological research has shown that people who stutter process speech and language slightly differently than those who do not stutter); and family dynamics (high expectations and fast-paced lifestyles can contribute to stuttering).

A weekly podcast where the hosts talk openly about stuttering and interview people who stutter and leaders in the field
Self-Therapy for the Stutterer, 12th edition, is a highly regarded resource and available for free download through the Stuttering Foundation
The Stuttering Foundation: A Non-Profit Organization with Resources, Information and Inspiration
The benefits of speech therapy
Children: The Lidcombe Program for stuttering is an evidence-based treatment involving collaboration with parents and progressing through stages. Frequency of treatment is weekly, with clinician intervention and parent coaching. Duration of treatment depends on meeting criterion to progress to the next stage in treatment. This is the model used at Two-Way Street. For a good overview of the Lidcombe treatment program, follow this link:

Adults: There are many theoretical models of treatment available for treatment. Two-Way Street utilizes the work of David Daly, a speech-language pathologist and former stutterer, who has dedicated the 30 years of his professional career to researching and treating people who stutter. Daly's fluency enhancing techniques are combined with oral-motor exercises to improve coordination of the oral movements involved in producing speech, almost always a factor in an individual who stutters. Treatment progresses through stages and is guided by the speech-language pathologist.
Resources and Links
on Stuttering
Treatment for Stuttering