Abstract only In resource‐limited settings, we generally assume that household food insecurity (HFI) status is static over time, ranging from a period of a few months to a few years. Longitudinal HFI measures are required to test the validity of this assumption. We assessed HFI on a monthly basis in the context of an efficacy trial of biofortified maize conducted in rural Zambia from October 2012 to March 2013. This period is mostly characterized as the lean season, which peaks in ~April in this setting. The trial included two intervention arms and a parallel non‐intervened group for the purposes of background dietary and food security measures. A total of 907 households were enrolled at baseline; however, the present analysis includes longitudinal data from 157 households in the non‐intervened arm. At each of the six monthly visits, HFI was assessed using a validated 8‐item perception‐based Likert scale with a one month recall period. We calculated a HFI index by summing scores over the Likert scale (ranging from 0 to 32). The median (IQR) HFI index was 7 (4–11), 8 (5–11), 7 (4–10), 6 (4–9), 6 (4–9) and 7 (4–9) at the six monthly visits, respectively. The correlation between HFI index between visits ranged from 0.3 to 0.4. A random effect model was fit on the index as a function of visit clustered at household level. Results from the model showed that the HFI index decreased on average by 0.25 points per visit. Within and between household variation in the index was 10.6 and 8.8, respectively. Within‐household variability of the HFI index did not show a clear pattern in relation to the household mean score. Because our repeated HFI measurements were conducted in one single season, the small change in mean monthly HFI index suggested that seasonal assessments may be sufficient for population monitoring purposes in similar settings. However, higher variation within some households suggests that household characteristics—as opposed to seasonal impacts on food security—may explain the differences in variation in response to the repeated scale. Support or Funding Information HarvestPlus (grant 8251) and Sight and Life Global Nutrition Research Institute at Johns Hopkins University