"This comment revisits a seminal 2001 paper by Donohue and Levitt (henceforth DL) that linked the startling and unexpected decline in crime during the 1990s to the legalization of abortion some 20 years earlier. DL theorize that abortion reduces crime for two reasons. First, holding the number of pregnancies constant, a higher abortion rate today reduces the number of young people in the future. Because younger people commit more crimes than older people, this “cohort-size” effect should reduce crime if the share of young people in the population declines. Second, because a mother can abort a pregnancy more easily when abortion is legal, a child born after legalization is more likely to be wanted than a child born before legalization. If children who are wanted grow up to commit fewer crimes than unwanted children do, then abortion will bring about an additional “selection” effect that further reduces crime."