Background: Despite the suggested benefits of shared decision-making (SDM), its implementation in policy and practice has been slow and inconsistent. Use of complex adaptive systems (CAS) theory may provide understanding of how healthcare system factors influence implementation of SDM. Methods: Using the example of choice of mode of birth after a previous caesarean section, in-depth, semi-structured interviews were conducted with patients, providers, and decision makers in British Columbia, Canada, to explore the system characteristics and processes that influence implementation of SDM. Implementation and knowledge translation principles guided study design, and constructionist grounded theory informed iterative data collection and analysis. Findings: Analysis of interviews (n=58) revealed that patients formed early preferences for mode of delivery (after the primary caesarean) through careful deliberation of social risks and benefits. Physicians acted as information providers of clinical risks and benefits, while decision makers revealed concerns related to liability and patient safety. These concerns stemmed from perceptions of limited access to surgical resources, which had resulted from budget constraints. Discussion and conclusions: To facilitate the effective implementation of SDM in policy and practice it may be critical to initiate SDM once patients become aware of their healthcare options, assist patients to address the social risks that influence their preferences, manage perceptions of risk related to patient safety and litigation among physicians, and enhance access to healthcare resources.