Given that many schools have limited resources and a high proportion of students who present with deficits in early literacy skills, supports aimed at preventing reading failure must be simple and efficient and generate meaningful changes in student learning. We used a randomized group design with a wait-list control to extend the work of Volpe, Burns, DuBois, and Zaslofsky (2011), who found a computer-assisted tutoring program designed to teach young children letter sounds using incremental rehearsal to be an efficient and acceptable intervention for students who were slow to respond to class-wide early literacy intervention. In our study, a total of 30 kindergarten and first-grade students were randomly assigned to either 2 weeks of computer-aided tutoring or a wait-list control group. The effects of the intervention were investigated using multiple-level modeling over four assessment periods (pre-treatment, 1 week of intervention, 2 weeks of intervention, and 1-week follow-up). Results were consistent across dependent measures, with rates of growth and follow-up scores significantly higher for the intervention group as compared with the control group. Given that these skills were enhanced in an efficient manner and maintained for at least 1 week, the computer-assisted tutoring intervention appears to be an appropriate support for rapidly improving early skill deficits related to letter-sound knowledge and decoding.