Objective:To determine if constraints on agricultural production were a novel construct in the Panama Food Security Questionnaire (FSQ) and to characterize agricultural and economic determinants of food insecurity during the planting, growing and harvesting time periods in subsistence farming communities.Design:This longitudinal study followed households during land preparation, growing and harvest periods in one agricultural cycle. Agricultural production and economic variables were recorded and the Panama FSQ was administered. Exploratory factor analysis was used to verify construct validity of the FSQ. A food insecurity score (FIS), ranging from 0 to 42, was derived. Multiple regression analyses of FIS were conducted for each agricultural period.Setting:Fifteen rural villages in Panama.Participants:Subsistence farming households (n 237).Results:The FSQ contained four constructs: (i) ability to buy food; (ii) decreased amount/number of meals; (iii) feeling hungry; and (iv) lower agricultural production because of weather or lack of resources. Although most households were mildly food insecure in all time periods, determinants of food insecurity differed in each. Higher FIS was associated during land preparation with less rice and legumes planted and lower asset-based wealth; during growing months with less rice, more maize and pigeon peas planted and not selling produce; and during harvest with less rice planted, fewer chickens and lower income.Conclusions:Constraints on agriculture was a novel construct of the Panama FSQ. Different income-related variables emerged in each agricultural period. Planting staple foods and raising chickens were associated with food security, but some crop choices were associated with food insecurity.