Food security is emerging as a key focus in developing countries and a determinant of socio-economic development. Rain-dependent agriculture, rain irregularities and variability necessitate the need to study the current status of food security, especially in semi-arid areas of Africa. This paper assesses food security in the rural context of Chamwino District, Tanzania. It adopts the sustainable livelihoods framework as its main tool of assessment under a mixed-method design for qualitative and quantitative analyses. It employs a simple random sampling technique to draw 385 agro-pastoralist households out of 13595. Likewise, it also applies a stratified sampling technique to ensure that appropriate number of elements are drawn from the homogeneous subsets of the population. Focus group discussions, in-depth interviews, transect walk and situational analysis mapping techniques were employed to ensure validity. Quantitative analysis was supported by the IBM SPSS software, version 20, to establish values of existing patterns. Qualitative data were subjected to content analysis to explore functions, attributes and drivers. The results suggest that Chamwino District has a chronic food insecurity history recorded from 1837 up to 2020. Most of the rural agro-pastoralists are victims of food insecurity even when agricultural productions are in surplus due to a wide range of factors. The magnitude of this problem is comparatively higher than in other districts in Dodoma Region. The intensity of the food problem is influenced by cash economy, the lack of technical education, limited diversity in reliable sources of income, and inadequate public utilities. Also, there are field-based evidences about the failure of the regulatory system to stimulate agro-pastoralism. [ABSTRACT FROM AUTHOR]