Research shows that third-grade reading proficiency is the most significant predictor of future success, including graduation rates, earning potential, crime, and health. Mastery of foundational literacy skills during preschool bolsters students' ability to learn to read before fourth grade when the transition from learning to read to reading to learn occurs. Preschool is beneficial, but not all preschool programs are the same. An extensive range of preschool programs exists with varying degrees of impact on reading preparation. This sequential design, mixed methods study compared data from a third-grade reading test to the type of preschool students attended when they were four years old. In the study's first phase, the researcher used inferential statistics to compare the mean composite Indiana Reading Evaluation and Determination (IREAD 3) scores to the type of preschool the students attended. In the second phase, the researcher used survey responses from preschool directors to learn more about the program's curriculum, scheduling, and staff training and credentialing. The researcher synthesized the qualitative and quantitative data from both phases to conclude that no specific type of preschool program will promote reading proficiency; however, if a preschool program has specific characteristics, the students are more likely to become proficient readers by the end of the third grade. The last chapter of this study provides readers with a list of recommendations to help stakeholders plan high-quality preschool programs that will set our youngest students up for long-term reading and educational success. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]