Despite extensive theoretical emphasis on the role of social capital, systematic quantitative evidence regarding the hierarchical impact of concurrent social mechanisms on sustainable regeneration in distressed urban fabrics of Iran’s intermediate cities remains limited. To address this gap, this study assesses the magnitude and direction of the effects of five social mechanisms on sustainable regeneration in the distressed urban fabrics of Khorramabad. Methodologically, this applied-developmental study employs a descriptive-survey approach. Data were collected via a researcher-designed questionnaire from 375 households using stratified random sampling and analyzed through Partial Least Squares Structural Equation Modeling (PLS-SEM). The results indicate that all examined social dimensions exert a positive and statistically significant effect on sustainable regeneration. The strongest direct effects were observed for social cooperation and security (β = 0.271, p < 0.001) and sense of place (β = 0.268, p = 0.007). Factor loading analysis further confirmed the multidimensional nature of regeneration, identifying social participation (λ = 0.817) as a pivotal indicator. Moreover, structural analyses revealed positive feedback loops: sustainable regeneration significantly reinforces sense of place (β = 0.718), while communication networks fundamentally underpin social trust (β = 0.705). Collectively, the findings suggest that social capital operates not merely as a byproduct, but as a structural prerequisite for the success of urban regeneration initiatives. Consequently, urban policymakers are advised to integrate physical interventions with “soft” strategies that enhance local governance and foster active resident participation.Collectively, the findings suggest that social capital operates not merely as a byproduct, but as a structural prerequisite for the success of urban regeneration initiatives. Consequently, urban policymakers are advised to integrate physical interventions with “soft” strategies that enhance local governance and foster active resident participation.