Given that the majority of college courses are staffed with instructors who have little, if any, teaching experience (Boysen, 2011), research has called for more innovative approaches to providing teaching development opportunities for graduate student instructors (GSIs) (e.g., BrckaLorenz et al., 2020; Chew et al., 2018). The purpose of this study was to explore professional learning communities (PLCs) as a potential solution to this challenge. This study employed an iterative action research design to develop a PLC of GSIs, explore their engagement in the PLC, and examine which aspects of the PLC were more or less engaging. Findings revealed several affordances and considerations related to PLCs and GSI teaching development. The PLC in this study was successful at engaging GSIs; however, different PLC activities engaged GSIs in different ways - behaviorally, affectively, or cognitively. Findings also revealed that how GSIs engaged was related to the design of each PLC activity, and specifically whether the activity supported five important motivational principles - value, autonomy, relatedness, perceived competence, and mastery goal orientation. Together, these findings suggest that, if designed intentionally to support motivational principles, PLCs do have the potential to engage GSIs in a variety of ways. Finally, these findings are situated in light of the conversation surrounding the challenge of GSI teaching development. Implications, limitations, and directions for future research are discussed. [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.]