The Nigerian primary school system has recently undergone a major change. School system change can be either piecemeal or systemic. Systemic change provides a framework for an all-inclusive model of change that relies on locally-driven, system-wide change guided by stakeholders through ongoing collaboration and joint ownership of the change process. Teachers are key roleplayers who can either positively or negatively affect the successful implementation of school system change. This research aimed to explore teachers' challenges in the introduction and implementation of systemic change in the Nigerian primary school system. We used system theory as the theoretical framework to inform the study. This qualitative study is located in a constructivist research paradigm. One-on-one semi-structured interviews were conducted with teachers. Teachers' challenges included the non-involvement of stakeholders in the change planning process, incorrect statistical data, inadequate funding, teacher demotivation, poor channels of communication, political influence, misappropriation and embezzlement of funds, and poor monitoring and evaluation of the change. Effective school system change requires a systemic approach to change that encompasses all tiers of a school system. The findings provide insight into how future change in the Nigerian primary school system could be conducted more effectively than in the past.