This chapter uses 2015–2019 data from the National Survey of Family Growth (NSFG) to present national estimates of sexual behavior for men and women ages 15–49 and measures of sexual attraction and sexual orientation for adults ages 18–49 in the United States. Based on a nationally representative, multi-stage probability sample of men and women ages 15–49 in the United States household population, NSFG data were collected through in-person interviews with a self-administered component at the end for the more sensitive survey content. Data from two NSFG releases (2015–2017 and 2017–2019) were combined to yield a final sample for 2015–2019 of 21,441 respondents ages 15–49 (11,695 women and 9746 men). National estimates for 2015–2019 are provided for sexual behavior with opposite-sex and same-sex sex partners, including vaginal, oral, and anal sex. These estimates are broken down primarily by age groups, marital/cohabiting status, educational attainment, and Hispanic origin and race. Measures of sexual orientation and attraction are shown for adults, along with concordance of these measures with types of sexual behavior. These data may be helpful in measuring populations at risk for sexually transmitted infections as well as providing insights about factors related to birth and pregnancy rates.