ABSTRACT. Objective: The purpose of this study was to determine whether the type of questions used to assess childhood sexual abuse (CSA) introduces systematic bias into estimations of the magnitude of the association between CSA and alcohol use disorders (AUDs). Method: The Semi-Structured Assessment for the Genetics of Alcoholism was administered by telephone to 3,787 female twins ages 18-29 years (14.6% African American, 85.4% White). Interviews included questions regarding sexual abuse experiences described in behavioral terms and a standard trauma checklist (in a separate section) with the items "rape" and "sexual molestation," with defi nitions provided in respondent booklets. (Fergusson et al., 1996a;Pereda et al., 2009;Vogeltanz et al., 1999;Walker et al., 2004), a well-documented risk factor for alcohol-related problems in adolescence and young adulthood (Fergusson et al., 1996b;Kendler et al., 2000;Silverman et al., 1996;Wilsnack et al., 1997) that is more common in families with an alcoholic parent (Anda et al., 2002;Dube et al., 2001;Fergusson et al., 1996a). Although a link between CSA and problem alcohol use has been reported relatively consistently, a range of methods have been used to assess CSA, which may contribute to variability in the estimated magnitude of the association reported in the literature. In the current study, we tested whether the magnitude of the association of CSA with alcohol use disorders (AUDs) varies as a function of assessment-specifi cally, if behaviorally defi ned questions about sexual abuse (read by an interviewer) yield different estimates than abuse terms such as rape presented with defi nitions in a trauma checklist (read by the respondent). Large-scale studies of alcohol use that cover a broad range of psychosocial domains are limited in the amount of time that can be devoted to the assessment of CSA and thus typically query CSA with one or two items using the terms rape, sexual abuse, or molestation. A larger number of cases of CSA are typically detected when behavioral descriptions of sexual abuse are used (e.g., "Did anyone ever make you touch their genitals when you didn't want to?") (Fricker et al., 2003;Lynch, 1996;Weaver, 1998;Wyatt and Peters, 1986), but it is not yet known whether using questions referencing abuse terms rather than behavioral descriptions of CSA biases results in studies of CSA and alcohol-related outcomes.The fi rst step in this line of inquiry is to determine the proportion of individuals who endorse behaviorally worded CSA questions who also endorse CSA when queried using abuse terms and the proportion of individuals who endorse abuse terms who also endorse behaviorally worded