This study featured validity evidence for scores from states' alternate assessments of alternate academic achievement standards (AA-AASs). It evaluated students from 6 states who were eligible for an AA-AAS concurrently with measures of academic competence and adaptive behavior. The investigators also assessed students with disabilities who were not eligible for an AA-AAS by using the same measures, as well as by using general achievement tests. The main findings included that AA-AAS reading and math scores may reflect a unitary construct, that AA-AAS scores are highly related to adaptive behavior but also relate to academic competence and achievement, and that all these scores represent unique but overlapping constructs. These results have implications for AA-AAS developers and teachers working with students with significant cognitive disabilities. (Contains 6 tables.)