A list of households with children 12-30 months of age (n=798) who were beneficiaries of the program in the 12 distribution clusters was provided by program officers at the beginning of the study. 510 of these children corresponded to the distribution clusters assigned to FM and 288 to the clusters assigned to NFM. The number of children in the FM clusters was larger for two reasons: more clusters were assigned to receive FM as a request from program officials who wished to minimize the number of children who would not receive the fortified milk immediately. In addition, some of the clusters randomly assigned to the fortified milk intervention served larger populations of beneficiaries. The parents or legal guardians of the 12-30 month old children were invited to participate and those who accepted signed an informed consent letter after a detailed explanation of the objectives, nature, and risks posed by the study. Prior to baseline measurements 33 children were excluded from the study (20 in the FM and 13 in the NFM groups) because they were either severely anemic (Hb concentrations < 90 g/L, n= 26) or refused to participate (n=7. Therefore, 765 children participated in the baseline measurements (490 in the FM and 275 in the NFM clusters). Between the baseline and the 6-mo follow-up measurements, 130 out of these children were lost to follow up for several reasons. Therefore 635 children completed 6 mo of follow up (n= 405 in the FM and 230 in the NFM groups). Between the 6-mo and the 12-mo follow-up measurements, 51 additional children were lost to follow up. Therefore 584 children completed 12 mo of follow up (n= 371 in the FM and 213 in the NFM groups).