INTRODUCTION:
Most health systems integration efforts in low and mid-income countries lack structured tools to measure maturity and guide iterative improvement. Uganda developed a national Health Systems Integration Maturity Framework (HSIMF) to benchmark progress across seven health system building blocks and to accelerate service integration reforms.

METHODS:
The HSIMF was developed through a multi-stage process: (i) literature review and conceptual mapping; (ii) stakeholder consultations through the National Advisory Committee on Integration; (iii) piloting using data from national technical supportive supervision (TSS) of 67 public health facilities; and (iv) iterative refinement and institutionalization. The framework defines five maturity levels from fragmented (Level 1) to fully integrated (Level 5) and is adaptable at national, sub-national and facility levels. Maturity scores were applied across domains: governance, financing, service delivery, HRH, HIS, supply chain and community engagement.

RESULTS:
Pilot application revealed partial integration nationally (Level 3). Supply chain and HMIS demonstrated the highest maturity (Level 4), reflecting long-standing cross-programmatic interoperability. Service delivery and HRH domains were intermediate (Level 3), reflecting shared staffing and consolidated clinic models. Governance and financing domains demonstrated early alignment but incomplete joint accountability mechanisms (Level 2–3). Community systems demonstrated minimal integration (Level 2), highlighting weak linkages between primary health care (PHC) platforms and community structures. The maturity framework clarified sequencing, identified domain-specific bottlenecks, and provided a structured agenda for institutional reforms.

CONCLUSIONS:
The HSIMF offers an applied health systems tool for measuring integration progress, enabling cross-domain benchmarking and guiding policy improvements. Maturity results informed the national integration agenda and contributed to ongoing reforms in planning, budgeting and supervision. Scaling the HSIMF nationally provides a pathway for LMICs transitioning from vertical programs toward integrated, people-centred systems. The tool can support donor transition, program sustainability, universal health coverage (UHC) commitments and cross-programmatic efficiencies.