The discourse identifying teachers as lifelong learners has challenged teacher educators to engage in continuous professional development (PD) activities. Moreover, the need to keep up with the ever-changing learning and teaching trends in today's era of technological innovations has further encouraged teacher educators in various contexts to seek new PD models that are not the traditional one-shot, one-size-fits-all demonstrations of a concept or method, often lacking in timeliness for the educators' needs. One such model is interactive online PD, in which participants construct and share rather than simply receive knowledge (e.g., Bragg et al., 2021; Britt & Paulus, 2016; (Lantz-Andersson et al., 2018; Sari, 2012; (Vangrieken et al., 2017; Wesely, 2013), specifically, teachers' online PD communities (e.g., Britt & Paulus, 2016). However, questions remain. For example, we know little about the nature of these online communities (e.g., is it a fan club or lifeboat?) or what members actually do to independently take charge of their PD and sustain their community engagement. Grounded within the frameworks of Community of Practice (CoP) (Lave & Wenger, 1991; Wenger, 1998, 2000; Wenger et al. 2009; Farnsworth et al., 2016), informal learning (Rogers 2014; Sackey et al., 2015), and self-directed learning (Garrison, 1997; Hiemstra & Brocket, 2012; Louws et al., 2017; Manning, 2007), the present study focused on a group of Indonesian English teacher educators who converged in an informal online learning community pseudonymously called the Professional Educators (the PE). The aims were to explore the kinds of community interactions within the PE, determine the factors that attracted teacher educators to participate in the PE and remain involved, and examine norms and values held by the PE members that helped them achieve successful community engagement. In particular, how writing and publication expectations, including governmental external quality standards, shaped their conceptualization of and conversations about professionalism were examined. The findings revealed that the core characteristics of a working CoP -- domain, community, and practice -- were strongly evident in the PE. The findings also demonstrated some essential factors that attracted people to join and stay in the community and norms/values that the members upheld to help them stay on track as they pursued their PD goals collaboratively. Interestingly, the results further revealed that PE members responded to the government's external quality measures in a somewhat contradictory way. On the one hand, they utilized their community as a platform to air their criticisms, articulate their actual PD needs and work together to achieve those needs. On the other hand, they still had to adhere to the government's regulations. Overall, this inquiry further suggests the potentials of community-based online PD for English teacher educators within the context of Indonesia and beyond. Some key implications of the findings are also addressed. [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.]