The relationship non-traditional school calendars have on student academic success has long been a topic of discussion among educational decision makers. Many early American schools operated on a non-traditional calendar year. Non-traditional school calendars typically operate on a normal 175-180 cycle of formal instruction; however, unlike the traditional calendar which has a long summer break, the year is broken into a series of shorter breaks. Few studies are annotated regarding the relationship to academic success and the type of calendar that is utilized. Currently, over 400 school districts across the United States operate on some of alternative school calendar. Studies within these districts have indicated some correlation between non-traditional calendars and student achievement especially among students of low socio-economic status. The purpose of this quantitative comparative study was to evaluate the relationship of school calendar and student academic achievement within four Title 1 schools in New Mexico. This study was an ex post facto study consisting of Partnership for Assessment of Readiness for college and Career English Language Arts data obtained from four Title 1 elementary schools within the state. Statistical Packages for the Social Science software was used to conduct a two-way between subjects' ANOVA. Analysis of the data indicated that there was no statistical significance in academic achievement between schools operating on traditional and non-traditional calendars. There was a statistical significance between male and female students attending traditional and non-traditional calendar schools, and there was a significant interaction effect between male and female students attending traditional and non-traditional calendar schools with p=.003. Implications for the study include information which may be beneficial to educational leaders in finding strategies that promote academic achievement. Recommendations for practice includes monitoring the academic achievement of both male and female students within this school over a longer period of time to better understand the relationship, if any, of instructional time (calendar) on student achievement among the sexes. Recommendations for future research include implementing a longitudinal study which follows a sample group of students attending traditional and non-traditional calendar schools from third grade through high school in various districts across the country.