This validity study examined the validity of Assessment, Evaluation, and Programming System, 2nd Edition (AEPS^®), a curriculum-based, authentic assessment for infants and young children. The primary purposes were to: a) examine whether the AEPS^® is a concurrently valid tool for measuring young children's language, literacy and pre-math skills for accountability purpose and b) explore teachers' perceptions on using authentic assessment and standardized tests. This was accomplished through implementing both quantitative and qualitative methods. Findings from the study indicated (a) the AEPS^® is a concurrently valid (b) there were both advantages and disadvantages of using authentic assessment such as the AEPS^® and using standardized tests based on teachers' perceptions, however, the practical issues of using the authentic measure can be addressed by providing in-depth trainings to teachers and increasing teachers' familiarity with their children; and (c) families preferred authentic assessment such as the AEPS^® because it is easier.