Prevention of mother-to-child transmission of HIV (PMTCT) is the single most effective HIV prevention intervention in practice today. Nonetheless, little reliable empirical evidence exists on the behavioral effects of PMTCT. This paper documents the rapid expansion of access to PMTCT in Zambia during the period 2000-2007 and provides some of the first evidence on the change in reproductive behavior associated with PMTCT scale-up. The results of a primarily descriptive analysis suggest that PMTCT may have generated increases in knowledge about PMTCT and MTCT, large reductions in child mortality and pregnancy rates, and smaller changes in breastfeeding rates. However, additional research is required to address the potential endogeneity of PMTCT availability.