PROMPT (Prompts for Restructuring Oral Muscular Phonetic Targets) is a treatment approach that is widely used to improve sound production in children with speech impairments. This approach uses tactile cues to support and shape movements of the oral articulators in order to improve the production of individual sounds, syllables, words, and eventually connected speech. The underlying assumption is that tactile cuing will facilitate changes in articulator movements. This investigation examined articulator movement as well as the accuracy of speech production, before, during, and after a period of PROMPT treatment in a child with severe articulation impairment. A typically developing child was followed longitudinally as a control. The following research questions were addressed: (1) Does speech sound accuracy improve over an eight-week course of PROMPT treatment? (2) Does articulator movement (duration, displacement, velocity) change over an eight-week course of PROMPT treatment? The results revealed increased articulation accuracy and decreased movement duration, displacement, and velocity over the course of PROMPT treatment in the child with the articulation impairment. By the last treatment session, kinematic findings were most similar to those seen in the control. These results suggest that PROMPT facilitated changes in articulatory control in a single participant.