Key Social Norms Take-aways Child marriage in southern Bangladesh is sustained by deeply entrenched and interconnected social norms—particularly those linking family honor to girls’ sexuality, expectations of female purity and obedience, and beliefs about girls’ limited social and economic roles. These norms constrain girls’ agency, justify parental control, and normalize early marriage as a protective and socially acceptable practice. Importantly, norms operate across multiple levels (individual, family, community, institutional), reinforcing each other and requiring multi-level interventions to shift them effectively.

Objectives This study aimed to explore the multi-level drivers of child marriage using a social-ecological model, examining how individual, familial, community/social norms, and institutional factors interact to shape child marriage practices in southern Bangladesh.

Methods The study used an iterative qualitative design grounded in the social-ecological model. Data were collected through 29 focus group discussions, 44 in-depth interviews, and 10 key informant interviews with adolescent girls (married and unmarried), parents, grandparents, community members, and local leaders. Thematic analysis was conducted using both inductive and deductive coding aligned with SEM domains.

Results Findings show that drivers of child marriage are interconnected across multiple levels. At the individual level, girls’ limited agency, lack of collective efficacy, and educational performance influenced marriage decisions. At the family level, poverty, gendered preferences favoring boys, and desire for economically advantageous marriage proposals were key drivers. At the community level, strong social norms around family honor, control of girls’ sexuality, perceptions of the “ideal bride,” and fear of violence constrained girls’ mobility and reinforced early marriage. Religious beliefs and patriarchal norms further justified marriage as a moral duty. Institutionally, weak enforcement of child marriage laws, legal loopholes, limited job opportunities for women, and external shocks (e.g., COVID-19, natural disasters) exacerbated risks.

Conclusions Child marriage is driven by a complex interplay of social norms and structural factors across ecological levels. Effective prevention requires coordinated, multi-level interventions that address harmful gender and social norms, strengthen institutional enforcement, expand economic opportunities for girls, and improve community awareness. Addressing only one level is insufficient, as norms and structural drivers reinforce each other in sustaining the practice.