Social deterioration refers to a process in which the quality, stability, or functioning of social relationships, institutions, community networks, and collective life progressively declines ^[1][2]. It may involve weakening social cohesion and trust, reduced participation and cooperation, disruption of established social ties, or declining capacity of communities and institutions to address shared needs ^[1][3]. At the neighborhood level, social deterioration may occur alongside population loss, socioeconomic disadvantage, reduced public or private investment, declining services, social disorder, or other changes that negatively affect residents’ social environment ^[2][4]. These processes can reinforce one another, as declining social conditions may reduce community engagement and collective capacity, which can further weaken local social organization ^[2][4]. Social deterioration is context-dependent and does not necessarily imply the complete breakdown of social relations; communities may retain strong social networks or develop new forms of solidarity while experiencing decline in other dimensions ^[3]. The term therefore describes a broad deterioration in the social conditions and relationships that support community integration, participation, and collective functioning.