@article{Stone_49_29, author = {Stone, Lyman}, title={{Ultra-Orthodox fertility and marriage in the United States: Evidence from the American Community Survey}}, journal = {Demographic Research}, volume = {49}, number = {29}, pages = {769--782}, doi = {10.4054/DemRes.2023.49.29}, year = {2023}, abstract = {Background: Amid low fertility rates in the industrialized world, some subpopulations have maintained high fertility rates. However, it has often been difficult to study these populations due to limitations in extant data sources. Objective: This paper will demonstrate a method of measuring key demographic indicators for Ultra-Orthodox Jews using demographic and language variables in the American Community Survey (ACS). Methods: Comparison of estimates of total fertility rates derived from ACS estimates of Yiddish and Hebrew speakers to related indicators from small surveys of American Jewish populations and data on same-sect fertility in Israel and the United Kingdom validates the use of Yiddish to identify Ultra-Orthodox Jewish respondents in the ACS. Results: ACS-derived demographic estimates for Yiddish speakers closely approximate estimates derived for Ultra-Orthodox Jewish communities using other methods. Ultra-Orthodox Jews in America have high fertility but very low rates of teen fertility and marriage, and fairly egalitarian marriage ages. Ultra-Orthodox Jewish fertility is high but not necessarily uncontrolled. Conclusions: ACS language data can be used to study relatively small subpopulations with unique demographic characteristics. Contribution: Researchers can use ACS language data to study other demographically unique subpopulations or to study Ultra-Orthodox Jews in more detail than was previously possible. }, URL = {https://www.demographic-research.org/volumes/vol49/29/}, eprint = {https://www.demographic-research.org/volumes/vol49/29/49-29.pdf} }