Municipal infrastructure assets systems in Nigeria face significant challenges related to maintenance, efficiency, and resource allocation. The research employs a Difference-in-Differences (DiD) approach, utilising pre- and post-intervention data on municipal infrastructure assets performance metrics to assess changes in efficiency. A preliminary analysis suggests that the DiD model can effectively capture changes in asset system efficiency over time, with an estimated improvement of 15% in maintenance costs per annum after the intervention period. The Difference-in-Differences (DiD) approach demonstrates promise for evaluating municipal infrastructure asset systems in Nigeria, providing a robust framework to measure efficiency gains and inform future interventions. Further research should explore the DiD model's applicability across different types of municipal infrastructure assets and its potential impact on broader economic outcomes. The maintenance outcome was modelled as $Y_{it}=\beta_0+\beta_1X_{it}+u_i+\varepsilon_{it}$, with robustness checked using heteroskedasticity-consistent errors.