The purpose of this study was to compare elementary classroom teachers' actual practice and perceived importance of English Language Arts professional development in five professional development dimensions: alignment, content and modeling, active learning, collaboration, and follow-up, in high and low mastery, low needs schools. The schools selected for this study were identified as low need and had 10 percent or less Free and Reduced lunch. These selected schools were then ranked according to the percentage of students who scored a level 4 on their 5th grade New York State English language Arts exam. High mastery level schools were schools that had a high percentage of students scoring a level 4 on the English Language Arts Exam for 5th grade. Low mastery level schools were schools that had a small percentage of students scoring at a level 4 on the English Language Arts Exam for 5th grade. Further, this study investigated if the differences in these teachers' descriptions of English Language Arts professional development of the five professional development dimensions: alignment, content and modeling, active learning, collaboration, and follow-up, predicted their placement in a high mastery level school or low mastery level school. This study found that there is no difference between the high mastery schools when compared to the low mastery schools in the five professional development dimensions of alignment, content and modeling, active learning, collaboration, and follow-up. [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.]