The Early Intervention Reading Software Program encourages literacy growth and achievement in students in grades K-3. The program addresses early reading through the use of computer-based literacy software which provides individualized instruction designed to supplement students' classroom learning. During the 2018-2019 school year, these software programs were used in 88 local education agencies (LEAs) and by approximately 124,378 students. The schools use the software to build literacy skills for all students in kindergarten and first grade, as well as for intervention with students in second and third grade. The evaluation studied two aspects of the program: (1) students use of the program during the school year ("program implementation"); and (2) the effects the program had on increasing students' literacy achievement ("program impacts"), including program effects across all four software programs (program-wide) and between each software vendor (vendor-specific). The program had a positive impact on students' literacy development in kindergarten, regardless of their program dosage, and in kindergarten and first grade for students who used the program based on vendors' recommended dosage, as measured by students' Acadience Reading composite scores. Kindergarten and first grade program students who met vendors recommendations also scored higher than their control group counterparts on all literacy skill areas measured for their grade level.