In Ethiopia, 95 % of total agricultural output comes from some 11 million smallholder farmers. A relatively significant proportion of the food grown in the country is stored at the household level by smallholder farm households, mainly for own consumption. Storage losses, generally perceived to be high, have significant implications for household food security. This study provides a microeconomic perspective of commodity storage, post-harvest losses (PHL), and food security in Ethiopia. It relies on a large-scale household panel dataset, the Ethiopia Socioeconomic Survey (ESS), which comprises 4,000 households in rural areas and small towns that are representative of the most populous regions of Ethiopia. The data were collected as part of the World Bank’s LSMS-ISA project; it involved three “waves” or collection periods: 2011/12, 2013/14, and 2015/16. Data from only the second and third waves were used to estimate a random-effects probit model. Findings show that the magnitude of PHL is substantial: damage is due to rodents and rotting related to traditional storage facilities, poor ventilation, humidity/temperature, and undesirable post-harvest handling. Findings also show that PHL decreases with better market access and improved storage practices. Mitigation measures that improve and promote modern grain storage facilities appear to provide a double dividend – reducing PHL while addressing food insecurity.