BACKGROUND: Accreditation is a key feature of many medical education systems, helping to ensure that programs teach and assess learners according to applicable standards, provide optimal learning environments, and produce professionals who are competent to practise in challenging and evolving health care systems. Although most medical education accreditation systems apply similar standards domains and process elements, there can be substantial variation among accreditation systems at the level of design and implementation. A discussion group at the 2013 World Summit on Outcomes-Based Accreditation examined best practices in health professional education accreditation systems and identified that the literature examining the effectiveness of different approaches to accreditation is scant. Although some frameworks for accreditation design do exist, they are often specific to one phase of the medical education continuum. MAIN TEXT: This paper attempts to define a framework for the operational design of medical education accreditation that articulates design options as well as their contextual and practical implications. It assumes there is no single set of best practices in accreditation system development but, rather, an underlying set of design decisions. A "fit for purpose" approach aims to ensure that a system, policy, or program is designed and operationalized in a manner best suited to local needs and contexts. This approach is aligned with emerging models for education and international development that espouse decentralization. CONCLUSION: The framework highlights that, rather than a single best practice, variation among accreditation systems is appropriate provided that is it tailored to the needs of local contexts. Our framework is intended to provide guidance to administrators, policy-makers, and educators regarding different approaches to medical education accreditation and their applicability and appropriateness in local contexts.