Data from the World Fertility Study were analysed to determine the effect of breastfeeding and child spacing on infant mortality. It was shown that at least in developing countries breastfeeding and spacing of children more than 18 months apart are inverse correlates of infant mortality. It was further determined that these results are supported even if data obtained by retrospective interviews concerning birth periods and dates of death are suspect. The results also seem to be general even though there is some variation between countries.