Foster care placement is among the most tragic events a child can experience because it more often than not implies that a child has experienced or is at very high risk of experiencing abuse or neglect serious enough to warrant state intervention. Yet it is unclear how many children will experience foster care placement at some point between birth and age 18. Using synthetic cohort life tables and data from the Adoption and Foster Care Analysis and Reporting System (AFCARS), we estimated how many U.S. children were placed in foster care between birth and age 18, finding support for three conclusions. First, up to 5.91% of all U.S. children were ever placed in foster care between their birth and age 18. Second, Native American (up to 15.44%) and Black (up to 11.53%) children were at far higher risk of placement. Foster care is thus quite common in the U.S., especially for historically disadvantaged racial/ethnic groups. Third, differences in foster care placement were minimal between the sexes, indicating that the high risks of foster care placement are shared almost equally by boys and girls.