<![CDATA[Teacher professional development (PD) programs in many schools remain dominated by one-directional, short-term training formats that show limited impact on instructional practice. This conceptual paper aims to build a model of teacher PD that integrates Knowles' six principles of andragogy with three evidence-based contemporary approaches: professional learning communities (PLCs), instructional coaching, and the strengthening of autonomous motivation grounded in self-efficacy. Using a literature synthesis method, the study combines classical adult learning theory, effective-features framework, motivation theory (self-determination theory and self-efficacy), transformative learning theory, and meta-analytic evidence on coaching and PLCs to produce a coherent, evidence-based framework. The result is the Reflective-Collegial Teacher Professional Development Model (PGRK Model), comprising five dimensions: reflective self-readiness, collegial experience through instructional coaching, contextual problem orientation through PLCs, autonomous motivation grounded in self-efficacy, and sustained tiered mentoring, accompanied by five theoretical propositions for future empirical testing and a mapping of the model against established PD frameworks. The study contributes theoretically by bridging andragogy, motivation theory, and contemporary PD practice, and practically by offering schools and policymakers an evidence-based, participatory, and sustainable alternative for designing professional development programs.]]>
