This study explored if the AP World History: Modern Reading is effective teacher professional development and if it impacts teachers and students. Desimone's Core Conceptual Framework served as the foundation for which to evaluate professional development. Adult learning theory served as the theoretical framework. The researcher used a mixed methods explanatory sequential design. A survey was completed by 83 AP World History: Modern high school teachers who had attended the AP World History: Modern on-site Reading. The survey provided data on teacher perceptions of the Reading as well as the perceived impacts on student learning. The researcher then conducted a focus group discussion with eight participants to study teacher perceptions and the impact on student learning in greater depth. Quantitative and qualitative results were integrated in order to gain a deeper understanding. The researcher found that attending the AP World History: Modern on-site Reading is beneficial teacher professional development. The structure of the in-person Reading allows for collaboration, engages participants and is relevant to the attendees' classroom practice. As a result of attending the Reading, teachers perceive increases in their knowledge and understanding of exam requirements, and they perceive increased levels of confidence in their abilities to instruct students and assess student learning. Teachers perceive that attending the AP World History: Modern Reading improved their students' scores and contributed to growth in student learning. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]