Decades of research have elucidated the practices associated with effective professional development (PD) for educators, yet evidence suggests that school practices in the United States do not regularly meet these criteria, and even when they do, they may not have the desired effect on student outcomes (Darling-Hammond et al., 2017; Didion et al., 2020; Easton, 2008; Fullan, 2007). This qualitative case study aimed to develop a more complete understanding of a relatively new approach to PD that reframes professional development as professional learning and engages teachers as agents in defining, pursuing, and evaluating individual learning goals. Specifically, this study explored one school's approach to supporting a model of self-directed professional learning. In this model, teachers set and pursued personal professional learning goals while the school provided dedicated time and resources. Framed by complexity theory, this study's research questions examined how a school-supported model of self-directed professional learning impacted teachers' instructional practices and how school-based and individual teacher-level affordances served to support the professional learning model. Study results suggested that the school's model of self-directed professional learning had both direct and indirect impacts on teachers' instructional practices. In addition, multiple affordances supported professional learning that impacted teachers' instructional practices. At the school-level, relational affordances, structural affordances, and cultural affordances served to support teacher learning. At the individual teacher-level, affordances included teachers who were passionate, invested, persistent, reflective, and collaborative. Ultimately, the study indicated that school-supported models of self-directed professional learning are interdependent systems, balancing acts between individual and collective efforts, and require cultural and mindset shifts. These findings have multiple implications for practice and collectively serve to underscore the importance of (1) designing professional learning models for all levels of the school system, recognizing the role of teachers' internal characteristics and external school-based supports, (2) articulating a clear shared vision for student learning and then trusting in teachers' ability to pursue related learning goals, and (3) involving teachers as active participants and leaders in designing and implementing the model. [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.]