Research about the positive value of self-regulated learning (SRL) has a strong presence in the literature. SRL is also prevalent in professional education courses, school-improvement plans and national curricula. However, SRL initiatives experience similar problems to many other school-improvement efforts. Initiatives begin with fanfare, enthusiasm, and resource commitments. But too often school-improvement initiatives taper off, leaving barely any trace of their initial mission. This leads to wasted resources and change fatigue.School-improvement initiatives might fail to sustain due to stagnant school systems. Schools that successfully sustain improvement-initiatives are complex systems that seek and respond to feedback and continuously adapt. Iterative refinement of new knowledge and practices replace existing behaviours, leading to systemic changes that accommodate the goals and practices of a school-improvement initiative such as integrating SRL throughout the curriculum. Our study investigated theoretical and practical conditions that enable sustained implementation of school-improvement initiatives. We undertook a scoping review of the education and implementation science literature in conjunction with extended interviews with over 60 educational leaders and practitioners in South Australia. We asked interviewees to elucidate their theories and strategies that enabled their own school-improvement initiatives to sustain over longer terms. We adopted a complex adaptive systems perspective to thematically code (using NVivo) the reviewed literature and over 100 hours of transcripts.Results show a broad range of conditions for sustainable implementation. Examples include strategic, documented systemic planning; data collection and feedback to the whole school community; distributed all-level leadership; and commitment to innovation. Theoretical components for sustainable implementation were broadly relevant to all sites. However, actual implemented strategies were typically limited in scope within individual sites.From our synthesis of the interview data and literature we propose a theoretical framework of 20 conditions essential for sustainable school-improvement. We operationalise the 20 conditions into an online tool for schools that can be used at all stages of implementation cycles; through repeated planning, action, evaluation and adaptation. Used over time, the tool can evaluate system change when new initiatives, such as developing teachers’ epistemic knowledge about SRL, or explicitly teaching SRL strategies such as reflection and self-checking to students, become embedded into a school’s system and culture.The key recommendation from our research is to conceptualize and evaluate school-improvement as a continuous whole-system process rather than as a relatively short-term end-product of any singular initiative. Acting on this recommendation can potentially improve the sustainability of school-improvement initiatives about SRL.