The focus of Phase 1 was to examine the construct validity of the PA KEI. Evidence of construct validity refers to scientific evidence that the items within an assessment operate in a manner that is aligned with the domains that the PA KEI purports to measure. The Phase 1 research questions are as follows: 1. What are the characteristics of the PA KEI indicators? 2. Does the PA KEI measure five distinct dimensions of children's competency at kindergarten entry? If not, what are the evidence-supported dimensions? 3. Within each of the identified dimension structures, do the PA KEI indicators function as expected? 4. Do the dimensions of the PA KEI operate consistently across relevant subgroups of children (i.e., gender, race, children with special needs, and dual language learners)? Given the results of Phase 1, OCDEL decided to pursue a concurrent validity study during Phase 2 (Path A). Phase 2 assessed the concurrent validity of the evidence-based dimensions derived from Phase 1 using other independent, validated measures of children's knowledge and skills at kindergarten entry. A concurrent validity study examines the relationships between the dimensions of a measure under investigation and existing validated measures of similar and dissimilar dimensions. This phase also included an examination of how much variation in children's PA KEI scores (derived from teachers' ratings of children in their classroom) is directly attributable to the child rather than to between-classroom sources of variability, such as teacher characteristics (e.g., experience) or the context within which children are rated (e.g., large and small classrooms). The Phase 2 research questions are as follows: 5. Do the evidence-based PA KEI dimensions validated by the construct validity study correlate with other validated kindergarten assessments of similar constructs? 6. To what extent do the scores reflect information about individual children? Collectively, the findings of the construct validity study and the concurrent validity study provide scientific evidence to support conclusions related to three key areas of inquiry: (1) the scientifically supported dimensions of the PA KEI; (2) the evidence-supported uses of the PA KEI; and (3) recommendations for next steps in the continuous quality improvement of the PA KEI. (author abstract)