To determine whether or not limited caregiver health literacy is associated with adherence to a daily multi-vitamin with iron regimen in infants.110 caregiver/infant dyads were enrolled in a prospective study to assess the relationship between caregiver health literacy and adherence to a daily multi-vitamin with iron regimen for infants. Households were contacted biweekly over a 3-month period. Adherence was based upon caregiver report. High adherence, our primary outcome, was defined as the administration of the multi-vitamin with iron on 5–7 days over the past week.As measured by the Short Test of Functional Health Literacy in Adults (S-TOFHLA), 18% of caregivers had limited health literacy skills. Caregivers with limited health literacy skills were more likely to have higher adherence than caregivers with adequate health literacy, after adjusting for a number of possible confounding variables (AOR=2.13; 95% 1.20–3.78).Caregivers with limited health literacy were twice as likely to report high adherence to a daily multi-vitamin with iron regimen in infants as caregivers with adequate health literacy in adjusted analysis.Health literacy may exert a differential influence on adherence depending upon the complexity of the desired health behavior.