This descriptive study investigated the development of the 5 dimensions of the professional learning community model in 5 economically disadvantaged and diverse Texas elementary schools, which demonstrated improvement in student achievement on the Texas Assessment of Knowledge and Skills (TAKS) over a 5-year period. The purpose of this study was to determine the level of the development of the 5 dimensions of the professional learning community model in improving exemplary Texas elementary schools and to identify and compare the possible commonalities and differences existing between the schools on the 5 dimensions of professional learning communities. The method used in this study was a mixed method approach. The findings from this study suggest that sustainable systemic professional learning communities result from school cultures fostered by relationships of trust and mutual respect where teachers and principals collectively learn together improving school culture and increasing student achievement.