This article demonstrates a method for collecting data on adolescents' social knowledge related to sex by conducting an interview which elicits the meanings of vernacular terms. The purpose of the interview is to determine how behavior related to sex is planned and interpreted. Short answer questions at the outset of each interview are used to elicit vernacular terms. The interviewer starts by identifying a term and asking its meaning. The interviewer then seeks to determine how the term is used in colloquial speech. As the interview progresses, the interviewers develops a provisional model of concepts and assumptions which underlie the term. Techniques such as paraphrasing and eliciting criteria and exceptions are used to test hypotheses related to the model. A key dimension of the inquiry has to do with the identification of models of persons and behaviors encompassed by the meaning of the term. The interview is capable of determining expectancies and values linked to a target behavior. Interviews with an African-American male and a White female, both focused on the vernacular term "clean", are used to illustrate the method.