Many educational administrators in Georgia continue to struggle with low student academic achievement and low high school graduation rates. DuFour's professional learning community (PLC) theory suggests a positive relationship between levels of PLC implementation and academic achievement and between levels of PLC implementation and graduation rates. The purpose of the study was to further examine DuFour's theory by determining whether schools' levels of PLC implementation, as reported by principals, were statistically significant predictors of academic achievement and graduation rates, after controlling for school size, percentage of minority students, and percentage of free and reduced lunch. This problem negatively affects teachers, administrators, students, and stakeholders. However, the previous research on this theory has been inconclusive, partly because some report mere absence or presence of PLCs rather than level of implementation. Hord's "School Professional Staff as a Learning Community Questionnaire" was administered to Georgia high school principals to elicit the level of PLC implementation. Archival data on participating schools' academic achievement, graduation rates, and school demographics were collected. A multivariate analysis of covariance indicated a statistically significant relationship between degree of PLC implementation and academic achievement and graduation rates. However, the only statistically significant univariate difference showed a negative relationship between PLC implementation and academic achievement in English. The study provides information that educators can use to make decisions about implementing PLCs and, as a result, bring about positive social change through a more effective PLC construction. [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.]