Project Summary Spatial ability is one of three categories of basic abilities, along with verbal and quantitative abilities, that are the basis for developing everyday skills of independent living (Park, Lubinski, & Benbow, 2000). Verbal and quantitative abilities are prominently featured in school curriculum and assessments, whereas spatial ability has often been completely overlooked or received only limited attention. Based on available literature and our own preliminary research, we have concluded that persons with Down syndrome (DS) exhibit difficulties in utilizing the specific spatial abilities of mental rotation and perspective taking, and performing complex spatial tasks such as wayfinding and environmental learning. A weakness in spatial abilities may have many direct applications to daily life, ranging from activities such as tying shoes to using hand tools and navigating the environment. They also serve as a cognitive foundation for many other complex skills such as solving mathematical problems and using spatial language for giving and receiving directions. Moreover, they are used in a variety of specialty jobs such as grocery stocking, packaging, and assembling, which are among the most commonly reported jobs for adults with DS. Hence, a new focus on spatial ability and its modifiability in persons with DS is clearly warranted. The primary goal of the research proposed in this application is to evaluate the malleability of mental rotation and perspective taking in people with DS through providing intentional experience with numerous spatial activities. Two groups of participants will be tested over the course of the project: adolescents and young adults with DS and typically developing children. Following an initial evaluation of performance on the two abilities, participants will receive up to eight sessions of spatial activity experience utilizing puzzle construction, block building, and computer search tasks. Following the experience sessions they will be re-evaluated. These data will be used to investigate two specific aims. First, we investigate whether spatial abilities of persons with DS can be modified by experience with spatial activities. Second, we investigate whether the degree of modification observed for persons with DS can reduce performance differences between them and TD children. We also consider whether performance on the PPVT, KBIT matrices, and Chronological Age are associated with any benefits from spatial ability experience. To the best of our knowledge, this is the first study to use experience with spatial activities to improve spatial ability functioning in persons with DS, or persons with intellectual/developmental disabilities in general for that matter.