This study examines the impact of cultural attitudes on the fertility decisions of women who were born in the U.S. To distinguish the economic and institutional effects from the cultural effects on fertility decisions, this study employs data from second-generation immigrant women who kept their heritage languages in the U.S. Total fertility rate (TFR) from the woman’s heritage country is defined as a cultural proxy for fertility decisions. The results of the models indicate that second-generation immigrant women who kept their heritage languages and whose parents emigrated from countries with higher/lower TFR have more/fewer children in the U.S., respectively. Heritage cultures have positive and statistically significant impact on women’s fertility decisions. The two main findings indicate that first, culture has quantitative effects on a woman’s fertility decisions and second, culture slowly shifts over time. The results also demonstrate the importance of cultural transmission from one generation to the next, which can be used by policy makers.