This multiple-bounded case study explored charter-school music teacher practitioners' (MTPs') and instructional leaders' (ILs') perceptions of professional development (PD) in four charter management organizations (CMOs). The purpose was to provide a rich description of these practitioners' professional development, with the goal of spurring policy conversations and further research on music teachers and their experiences in the charter domain. Over two months in the fall of 2023, the researcher conducted one-on-one interviews with eight participants, which focused on ways of making change, methods of delivery, beneficial components of the methods of supporting music literacy, and forms of PD assessment from the perspectives of MTPs and ILs. In addition to holding two focus groups (one with each case), the researcher conducted four classroom and debrief observations. The interviews and observations were analyzed using the participants' words as first-cycle analysis themes; these were then filtered through the study's conceptual framework of Desimone's (2009) core elements of effective professional development: content focus, active learning, coherence, sustained duration, and collective participation. The findings illustrate the participants' experience with the professional development phenomenon through a series of main themes: instruction is classroom management, except when it is not, (b) the many moods of instructional coaching and workshops, (c) content expertise via cycles of inquiry, and (d) reflection is essential. Implications include framing future empirical research in this usually guarded sector as a partnership to identify best and emergent practices for practitioners that directly affect students and families. Framing research in this manner may resonate with charter management organizations that adhere to more formative professional development practices. Additionally, cycles of inquiry in which self-reflection can occur may be a way forward for myriad non-content-expert instructional leaders who support the professional development of music teacher practitioners in charter schools or traditional public schools. Further suggestions for future practice include hosting charter-specific sessions at music education conferences, which could be framed as dialogic sessions to foster collegial inquiry concerning practices at both charter and public schools. Because CMOs' system structures are different, practitioners there experience some aspects of teaching and professional development differently than their traditional public counterparts. Offering sessions specifically tailored to charter practitioners' needs could help ensure that their needs, as well as those of the ILs that support them, are met. [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.]