Reading Horizons partnered with LearnPlatform by Instructure to investigate the relationship between teacher implementation of Reading Horizons Discovery (RHD) and student literacy outcomes. The study involved 83 educators and 1,242 students across seven elementary schools in North Carolina during the 2022-23 school year. Researchers used mCLASS assessment scores (i.e., DIBELS Composite, phonemic awareness, letter sounds, decoding) to measure literacy achievement. Findings indicate that increased participation in RHD-facilitated professional learning correlated with higher spring literacy achievement in kindergarten and second grades. Furthermore, teachers who used more RHD core components reported greater teaching effectiveness. There were mixed relationships between the use of RHD core components and student literacy achievement. The current study offers promising results on the influence of RHD, with future studies ongoing in different contexts using correlational and quasi-experimental designs. [This report was prepared for Reading Horizons by LearnPlatform by Instructure.]