This report presents national estimates of several measures of sexual behavior, sexual attraction, and sexual identity among males and females 15-44 years of age in the United States, based on the 2006-2008 National Survey of Family Growth (NSFG). These data are relevant to demographic and public health concerns, including fertility and sexually transmitted diseases among teenagers and adults. Data from the 2006-2008 NSFG are compared with data from the 2002 NSFG and other national surveys.