months.) Wave 4 interviews were conducted from 2002 to 2005. Wave 5 assessments were conducted from 2005 to 2008. Of the 4,638 twins identified from birth records, 80% completed the Wave 4 interview (n=3,787), the primary source of data for the current study. Of these participants, CSA status was available for 3,761 (926 monozygotic twin pairs, 772 dizygotic twin pairs, and 365 individuals whose co-twins did not participate in the study). Mean age at Wave 4 was 21.7 (SD=2.8; range=18–29) years; 14.6% of participants self-identified as African American, the remainder as European American.
