This study estimated the prevalence of overweight and obesity in Mississippi public school students in grades K-12 and assessed changes in the prevalence between 2005 and 2013. In 2013, Body Mass Index was calculated using measured height and weight data for a weighted representative sample of 4,402 public school students. Additional analyses compared 2013 prevalence estimates by gender, race, and grade levels and for changes between 2005 and 2013. The prevalence of overweight and obesity among public school students no longer appears to be increasing although no significant downward trend was observed (p = 0.0862), and rates remain higher than national averages. In 2013, the combined prevalence of overweight and obesity for all students in grades K-12 was 41.8%, as compared to 40.9% in 2011, 42.4% in 2009, 42.1% in 2007 and 43.9% in 2005. Significant decreases in overweight and obesity were found among white students and elementary school students from 2005 to 2013. White students' combined rates fell from 40.6% in 2005 to 36.8% in 2013 (p = 0.0007). Similarly, combined rates in elementary school students dropped from 43.0% in 2005 to 38.0% in 2013 (p = 0.0002). Additionally, 2013 marked the first year that a significant decline in obesity prevalence was noted among elementary school students, from 25.0% in 2005 to 22.0% in 2013 (p = 0.0163). In 2013, the prevalence of obesity was significantly higher among black students (p < 0.001) and middle school students (p = 0.048). These findings are discussed in light of recent state-wide educational and policy initiatives and on health disparities. Implications for future practice, policy and research are presented.