This study was an attempt to assess preferences between a task arrangement involving mobility and a task arrangement involving sedentariness with three adults with multiple disabilities. Periods in which participants were exposed to both task arrangements were followed by periods in which they were allowed to choose between them. One participant had a strong preference for the task arrangement involving mobility from the beginning of the assessment. The other two participants developed a strong preference for the same task arrangement and showed higher levels of on-task behavior and/or of positive mood expressions within that arrangement. Aspects of the assessment as well as the use of assessment in daily contexts were discussed.