Decentralised and evidence-informed health systems rely on managers and practitioners at all levels having sufficient 'decision space' to make timely locally informed and relevant decisions. Our objectives were to understand decision spaces in terms of constraints and enablers and outline opportunities through which to expand them in an understudied rural context in South Africa. This study examined decision spaces within Mpumalanga Province, using data and insights generated through a participatory action research process with local communities and health system stakeholders since 2015, which was combined with published documents and research team participant observation to produce findings on three core domains at three levels of the health system. Although capacity for decision making exists in the system, accessing it is frequently made difficult due to a number of intervening factors. While lines of authority are generally well-defined, personal networks take on an important dimension in how stakeholders can act. This is expressed through a range of informal coping strategies built on local relationships. There are constraints in terms of limited formal external accountability to communities, and internal accountability which is weak in places for individuals and focused more on meeting performance targets set at higher levels and less on enabling effective local leadership. More generally, political and personal factors are clearly identified at higher levels of the system, whereas at sub-district and facility levels, the dominant theme was constrained capacity. By examining the balance of authority, accountability and capacity across multiple levels of the provincial health system, we are able to identify emergent decision space and areas for enlargement. Creating spaces to support more constructive relationships and dialogue across system levels emerges as important, as well as reinforcing horizontal networks to problem solve, and developing the capacity of link-agents such as community health workers to increase community accountability.