BACKGROUND: Organophosphates (OPs) are neurotoxicants used to control pests on crops (e.g., rice). Thai women farmworkers (∼23%) may be exposed during childbearing years. Previous literature documents adverse neurodevelopmental effects of prenatal exposure to pesticides although findings are inconsistent. OBJECTIVE: We evaluated the associations of prenatal OPs with measures of attention, memory, and information processing. METHODS: We recruited 323 mother/infant pairs and analyzed maternal urine for OPs (∑DAPs) during each trimester of pregnancy. Infants completed computerized tests of visual habituation (VH) (attention), visual paired comparison (VPC) (recognition memory), and continuous performance (CFT) (information processing). Adjusted regression models associated maternal biomarkers with infant measures. RESULTS: We did not find adverse effects of ∑DAPs associated with VH at 4 or 7 months. However, males in the highest relative to lowest tertile of 2nd trimester ∑DAPs did not exhibit the expected decline in speed of VH from 4 to 7 months. Overall ∑DAPs at 7 and 18 months were negatively associated with VPC for males and females with strongest associations for females. CFT trials to criterion were positively associated with ∑DAPs at 12 and 18 months particularly for males at 18 months, suggesting slower encoding. However, females achieved better performance on visual habituation and continuous familiarization associated with higher maternal ∑DAPs at 4 and 7 months, respectively. We also observed better performance for VPC among males and females at 12 months. DISCUSSION: Because infant visual attention, recognition memory, and information processing are predictive of later cognitive development such as emerging executive function, alterations associated with prenatal OPs could have long-term consequences for school readiness.