This study set out to define the normal maturation of the gut microbiome during the first 2 years of postnatal life. 50 children from four sites in the MAL-ED study: Brazil, India, Peru and South Africa. 1091 stool samples; V4 region of 16S rRNA gene. Prospective cohort design with monthly sampling for the first ~2 years of life. Additional clinical and epidemiologic data for the same participants is available at ClinEpiDB.org.