Supporters argue abstinence is the only fully effective way to prevent pregnancy and sexually transmitted infections, while critics contend students need information about contraception because many will become sexually active before marriage.
It's a school curriculum that focuses on encouraging students to wait until marriage to have sex, and usually does not teach about birth control methods.
Studies have reached differing conclusions about effectiveness, and both sides dispute how to measure outcomes and isolate the effects of curriculum from other social factors.
States can apply for Title V funds to implement abstinence-focused curricula, with requirements that programs teach the social, psychological, and health benefits of abstaining from sexual activity.
Some states require schools to stress abstinence when sex education is taught, while others mandate that any instruction be medically accurate or include information on contraception.
A look at how sex education is taught in U.S. public schools, who decides, and what the evidence shows.
Read the guide →States and school districts are divided over whether to mandate curricula that cover contraception, consent and sexual health alongside abstinence.
Read the brief →