Professional development (PD) plays a critical role in supporting teacher quality and retention, ultimately affecting student achievement. The pandemic has altered the traditional educational landscape for teachers, making effective PD essential. This qualitative study sought to explore an impact team model (ITM) of PD as an effective form of PD, its influence on teachers' self-efficacy relating to the four sources of self-efficacy and any instructional changes to their instructional practices after participating in the ITM PD. Findings indicated that honoring teacher time, collaboration, trust, positive feedback, and opportunities for self-reflection, contributed largely to the effectiveness of the ITM PD. The impact team PD provided a safe and trusting space for teachers to take risks and have discussions about instruction. The sessions yielded strong collegial relationships and increased collaboration outside of the PD sessions amongst the participants. In this study, all nine teachers reported shifts in instructional practices. Instructional practices involving classroom management and strategies to engage students have changed after experiencing this PD. Recommendations are offered based on the results of the study. [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.]