In this technical report, we provide the results of a series of studies on the technical adequacy of the early reading measures available on the easyCBM[R] assessment system. The results from the two-level hierarchical linear growth model analyses suggest that the reliability of the slope estimates for the easyCBM[R] reading measures are strong, with some exceptions. The growth reliabilities tend to decrease as grade-level increases, and were generally weaker for students who began the year as higher achieving, the latter of which could be explained by a ceiling effect. Results from the regression analyses examining the relation between the spring easyCBM[R] measures and the SAT-10 provide evidence supporting the concurrent and predictive validity of easyCBM[R] for grades K and 1. The models were statistically significant for both grades, explaining 73% and 58% of the variance in SAT-10 respectively. Finally, the overall predictive validity coefficients for the slope of improvement for all students in easyCBM[R] reading measures across grades were positive. Students with lower initial fall scores on the LS and WRF measures across grades (first and second quartile) had the highest rate of growth compared to other quartiles, with moderate predictive validity coefficients in the 0.50s and 0.60s. (Contains 38 tables and 2 figures.)