Child swearing is a largely unexplored topic among language researchers, although assumptions about what children know about taboo language form the basis for language standards in many settings. The purpose of the studies presented here is to provide descriptive data about the emergence of adultlike swearing in children; specifically, we aim to document what words children of different ages know and use. Study 1 presents observational data from adults and children (ages 1-12). Study 2 compares perceptions of the inappropriateness of taboo words between adults and older (ages 9-12) and younger (ages 6-8) children. Collectively these data indicate that by the time children enter school they have the rudiments of adult swearing, although children and adults differ in their assessments of the inappropriateness of mild taboo words. Comparisons of these data with estimates obtained in the 1980s allow us to comment on whether swearing habits are changing over the years. Child swearing data can be applied to contemporary social problems and academic issues.