The present study examined the applicability of the PCL:YV items to a sample of detained adolescent girls. Item response theory (IRT) was used to analyze test and item functioning of the PCL:YV. Examination of IRT trace lines indicated that the items most discriminating of the underlying construct of psychopathy included “callousness and a lack of empathy”, “conning and manipulation”, and “a grandiose sense of self-worth”. Results from the analyses also demonstrated that the items least discriminating in this sample, or least useful for identifying psychopathy, included “poor anger control”, “shallow affect”, or engaging in a “serious violation of conditional release”. Consistent with previous research (Cooke & Michie, 1997; Hare, 2003), interpersonal and affective components of psychopathy provided more information than behavioral features. Moreover, although previous research has also found affective features to provide the most information in past studies, it was interpersonal features of psychopathy in this case, followed by affective features, that provided greater levels of information. Implications of these results are discussed. Copyright © 2006 John Wiley & Sons, Ltd.