Three button design features (the shape, size, and position of a button on a garment), conceptualized as setting events, were evaluated in terms of their effect on the performance of buttoning skills in four developmentally retarded preschoolers. Utilizing a single-subject multi-element design, the 36 combinations of the three experimental variables (4 shapes, 3 sizes, and 3 positions) were systematically presented to the participants without any formal training. Results indicated that buttons of large size in the top position on the presentation garment maximally encouraged learning this self-dressing skill. Few consistent effects were attributed to the specific shapes examined. Analyses of the events disrupting buttoning perfor-mance, the frequency of uncompleted and mismatched button trials, as well as the number of requests for assistance emitted by the subjects, served to support these findings while yielding implications for future training and experimentation.