In the last decade, accumulating evidence from laboratories in the U.S. and Europe, as well as our own, led to the development of a multi-factorial model of stuttering. This model of stuttering hypothesizes that stuttering emerges from complex interactions among factors including genetics, language processing, emotional/social aspects, and speech motor control. Ultimately, stuttering occurs when the neural signals that produce the coordinated movements in the respiratory, vocal, and articulation systems become disrupted. The underlying notion is that the functions of the brain areas for speech motor control are affected by complex interactions with other neural systems. One important underlying assumption of this model is that these factors may not play the same role in different individuals who stutter and very likely vary in significance over different stages of development.