ObjectiveWe studied whether increased emergency contraception availability for women over age 18 was associated with a higher probability of risky sexual practices. DataA total of 34,030 individual/year observations on 3,786 women aged 18 and older were extracted from the National Longitudinal Survey of Youth, 1997 from October 1999 through November 2009. Study DesignWe modeled three binary outcome variables: any sexual activity; sexual activity with more than one partner; and any sex without a condom for women with multiple partners for women in states with state-level policy changes (prior to the 2006 FDA ruling) and for women in states subject to only the national policy change both jointly and separately. FindingsWe found different results when estimating the state and federal changes separately. The national change was associated with a reduction in the probability of sexual activity, a reduction in the likelihood of reporting multiple partnerships, and there was no relationship between the national policy change and unprotected sexual activity. There was no relationship between the probability of sexual activity or multiple partnerships for women in states with their own policy changes, but we did find that women in these states were more likely to report unprotected sex.