The purpose of this ex post facto study was to compare the effect the Read Well and the Reading Street curriculums had on achievement test scores. Data from the "Stanford Achievement Test, 10th ed." (SAT10) were examined using total reading scale scores for males and females at the kindergarten and first- and second-grade levels. Three research questions were constructed to determine if there were significant differences in the 2014-2015 SAT10 scores between male and female kindergarten, first-, and second-grade students who received Read Well instruction and male and female kindergarten, first-, and second-grade students who received Reading Street instruction. Data were gathered from students attending two Title I school districts in the southwest region of Tennessee. The researcher received the de-identified data from the research assistant which contained the students' SAT10 reading scale score measures from each school district's historical assessment data files. The scores were analyzed using a two-way ANOVA with the reading scores and gender as the covariates. Students were divided based on their grade levels. There were 195 kindergarten students, 213 first-grade students, and 191 second-grade students in this study. Results reported that while females scored higher than males, there were no significant differences in the 2014-2015 spring SAT10 total reading scale sores found between males and females at any of the grade levels tested. Results showed that kindergarten and first-grade Read Well students scored higher than kindergarten and first-grade Reading Street students. The results showed that second-grade Reading Street students scored higher than the second-grade Read Well students. The only significant difference between the two curriculum groups was found at the first-grade level, p = 0.000, with Read Well students scoring higher. [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://www.proquest.com/en-US/products/dissertations/individuals.shtml.]