In this paper we analyze the extent to which a mandated kindergarten assessment predicts 3rd grade outcomes, and the academic progression for students from 3rd grade to high school. We find that the kindergarten assessment strongly predicts 3rd grade outcomes, with the math skills assessment being especially predictive of 3rd grade academic outcomes. The kindergarten assessments also illustrate the degree to which there are large inequities in skills when students are assessed in kindergarten. Students from historically disadvantaged groups enter kindergarten with significantly fewer readiness standards met. Our analysis of student academic progression from 3rd grade through high school echoes the kindergarten to 3rd grade results. The 3rd grade test assessment is strongly predictive of all high school outcomes, and we see that those students eligible for free- or reduced-price lunches and students of underrepresented racial or ethnic groups are less likely to have upward academic mobility. In sum, we observed limited academic mobility; students who start out behind generally stay behind.