Sustainability assessment has become a crucial component of public policy, urban planning, and research on sustainable development. Most assessment methodologies remain predominantly outcome-oriented, evaluating the state of sustainable development while paying relatively little attention to the governance processes through which it is pursued. This paper argues that sustainable development may be understood and evaluated as a continuous governance process rather than solely as a set of societal outcomes. This study proposes the Governance-Centered Sustainable Development Assessment as a theoretical framework for evaluating sustainable development through governance rather than solely through outcomes. The framework posits four governance domains: governance capacity, governance implementation, governance effectiveness, and sustainable development outcomes within a unified governance architecture. A standardized methodology operationalizes this perspective integrating longitudinal archival data, governance activity coding, structured evaluation worksheets, evidence hierarchies, process tracing, and a municipal sustainable development governance maturity scale. The methodology is demonstrated through a longitudinal application to a city. This research advances an ontological reconceptualization of sustainable development as a governance process; and it extends program evaluation theories to sustainability governance by providing a structured, transparent and transferable framework for evaluating municipal governance processes alongside community outcomes. These contributions shift sustainability assessment from measuring how sustainable communities are to understanding how communities govern sustainable development.

Sustainability assessment has become a crucial component of public policy, urban planning, and sustainable development research. Most assessment methodologies remain predominantly outcome-oriented, evaluating community conditions while paying comparatively less attention to the governance processes through which sustainable development is pursued. This study develops Governance-Centered Sustainable Development Assessment (GCSDA), a theoretical framework that distinguishes four domains: Governance Capacity, Governance Implementation, Governance Performance, and Sustainable Development Outcomes. The Municipal Sustainable Development Governance Assessment Framework (MSDGAF) operationalizes GCSDA through longitudinal documentary analysis, evidence-based classification, process tracing, and governance maturity assessment. The framework is applied to the City of Laredo, Texas, using 468 regular City Council meetings from 2000 to 2025 and 13,259 governance observations. The findings reveal sustained institutional capacity and implementation alongside substantially less consistent evidence of organizational performance and community-level outcomes. Sensitivity analysis and longitudinal governance maturity analysis showed that the central longitudinal pattern remained stable despite marginal sampling variation. The study contributes to sustainability governance by distinguishing governmental capability and action from organizational performance and community conditions while maintaining a cautious relationship between municipal governance and outcomes influenced by broader contextual factors. It introduces a transparent and potentially transferable methodology, subject to cross-municipal validation, for longitudinal municipal research. GCSDA and MSDGAF complement outcome-centered sustainability assessment by providing a structured approach for examining how municipalities govern sustainable development over time.