Analyses will compare the nutritional and developmental outcomes of two groups who differ in iodized salt exposure, covarying confounders such as mother's education, family assets, child's sex, and adjusting for clustering. Developmental scores will be derived for the Bayley subtests, and the Wechsler Preschool and Primary School Intelligence test. These tests typically assign 1 point for every correct answer and 0 points for incorrect answers; the summed continuous scores are then used for analysis. Potential confounds include the Home Observation for Measurement of the Environment Inventory and Center for Epidemiologic Studies Depression Scale symptom scores, which also are calculated as the sum of individual item points. Laboratory analyses will be conducted to determine hemoglobin, ferritin, soluble transferrin receptor, thyroglobulin, thyroxin, and triiodothyronine from blood samples, and iodine excretion from urine samples. Analyses of salt will also indicate whether salt consumed by participants in the intervention districts has the required ppm of iodine and more than salt consumed in control districts. If households in the control sites have higher than expected levels of iodine, this will be recorded and included in the analyses.