Background and Purpose: The purpose of this study was to use single-subject research methods, combined with social validation procedures, as part of an evaluation/intervention process exploring the effects of adapted switch-operated devices on self-initiated behaviors of a 6-year-old child with profound multiple disabilities. Method: A single-subject withdrawal design with multiple phases, including one alternating treatments phase, was used to investigate the participant's ability to perform selective, voluntary motions as indicators of contingency awareness and preferences. Social validity also was assessed. Results: The child demonstrated the ability to use two switch sites to activate adapted switch-operated devices when a preferred stimulus was contingent on a specific motor action, and she demonstrated the ability to communicate preferences as indicated by more frequent switch activations for one consequence than for a second consequence. Social validity results indicated that both the parents and school personnel generally viewed the evaluation/intervention process as positive. Conclusions: Single-subject research methods, combined with social validation procedures, can be used effectively in the evaluation/intervention process for children with profound multiple disabilities. (Contains 1 figure and 1 note.)