The Renovation era in Vietnam (since 1986) has been a period of dramatic social change accompanied by large volume of internal migration. This study aims to identify a link between migration and the rapid decline of fertility levels among Vietnamese women in the last stage of the fertility transition in Vietnam. Data from the Vietnam Demographic and Health Survey 2002 was used to examine three theories of socialization, adaptation and migration on women’s fertility. These theories are examined by fitting both OLS and Poisson regression models for the number of children ever born. The results most strongly support the adaptation theory after controlling for education, age, age at marriage and wanted fertility. Women adapt to the fertility norms at their place of current residence to a greater extent than their place of birth. More specifically, among women born in rural areas, those who currently live in urban areas have 17 percent fewer children ever born than those who live in rural areas. This seems to be primarily due to adaptation to the new environment rather than to the act of migration itself, suggesting that migrating was not associated with lower or higher fertility during the Renovation era in Vietnam.