Mediating role of the regulatory framework in board accountability and sustainable growth of agricultural marketing co-operative societies in Simiyu, Tanzania

Sustainability remains a major challenge for Agricultural Marketing Co-operative Societies (AMCOS) in Tanzania, where governance is key to growth. This study examined how the regulatory framework mediates the relationship between board accountability and the sustainable growth of AMCOS in Simiyu Region. Guided by agency and institutional theories, the study employed a convergent parallel mixed-methods design. Data were collected from 237 AMCOS managers using questionnaires and from 6 District Co-operative Officers via key informant interviews (KIIs). Quantitative data were analysed with PLS-SEM, while qualitative data were thematically analysed. Findings indicated that board accountability moderately enhanced AMCOS growth, with effective monitoring, timely reporting, and transparent disclosure fostering trust and sustainability. The regulatory framework exerted a significant direct effect and mediated the accountability-growth relationship, highlighting its dual role. Among growth indicators, membership growth was strongest, whereas asset growth and product innovation remained weak due to limited resources, traditional business models, government dependency, and limited board capacity. The study concludes that AMCOS growth, mainly through membership expansion, is moderately driven by board accountability and strongly shaped by regulatory frameworks, while innovation and asset growth remain constrained. The study urges policymakers to balance enforcement with capacity building to strengthen innovation and stability in co-operatives.