The purpose of this mixed methods case study research was to investigate the reasons teachers chose online professional development (OPD) focusing on technology integration and how this OPD impacted teachers' classroom practices over a six month period. Previous research identified that OPD provides flexibility beyond what traditional face-to-face professional development provides for teachers. Catholic school, K-12 teachers participated in this study. Data was collected from surveys, interviews, and classroom observations. Survey data came from a pre-survey, post-survey, and follow-up survey. Survey data was analyzed quantitatively using dependent sample t-tests and a one-way ANOVA test. The case study data was collected throughout six months after OPD and came from interviews and three classroom observations of each of the two participating teachers. Five themes emerged from qualitatively analyzing the observation and interview data: (1) OPD provides hands-on opportunities, (2) OPD is practical for classroom implementation, (3) technology supports instruction, (4) classrooms are flexible and focus on student engagement, and (5) strong classroom management and organization. Quantitative data analysis results indicated that participants believe OPD is beneficial to professional growth, believe OPD provides and enhances their skills, feel comfortable transferring the OPD content knowledge into instructional practices, and believe OPD is as beneficial as or more beneficial than traditional professional development. This research study has implications for those who design teacher OPD and encourage participation in OPD as well as classroom technology integration. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]