First- and second-born adolescent siblings from 21 families completed a daily diary on each of 7 days. The frequency and content of siblings' conversations are described and the relationship between the content of siblings' discussion and their perceived academic, athletic, and peer competency is explored. Siblings most often talked about extracurricular activities, media, and academics. The remaining topics, friends, family, eating, and body image, were the focus of discussion less than 10% of the time. The extent to which siblings discussed extracurricular activities, media, and academics was connected to perceived competency. Discussion focuses on the sibling relationship as an important context for adolescent development.