The purpose of this report is to investigate the feasibility of constructing a school-level measure of students' academic growth from kindergarten to grade 3, and to assess the validity and precision of that measure. The study measured schoolwide student growth for reading and math using student growth percentiles based on Maryland's 2014/15 Kindergarten Readiness Assessment (KRA) and the 2017/18 grade 3 Partnership for Assessment of Readiness for College and Careers (PARCC) assessment. To assess validity, the study calculated correlations between student scores on the two assessments and compared those correlations with correlations between scores on tests in later years. To assess precision, the study constructed 95 percent confidence intervals around schools' growth estimates. Schools' K-3 growth estimates are likely less valid than schools' grade 3-4 growth estimates but have a similar level of precision. Schools' K-3 growth estimates are much less precise for smaller schools than for larger schools. Similarly, they are much less precise when they include only random samples of students as compared to all students in a school's relevant cohort. The study offers lessons to other states interested in constructing early grade growth measures using two different assessments that are administered multiple years apart. The following are appended: (1) a description of methods and (2) supporting analyses.