This article addresses children's sibling relationships as a site of social learning involving the (re)production of femininity and masculinity, drawing on in-depth qualitative interviews with children aged 8-12. We begin by noting the lack of focus on gender in the majority of previous work on siblings. After introducing our own study, we look at the ways in which children understood their siblings in relation to themselves, highlighting points of closeness and division, and pointing to class distinctions around individuality and collectivity. We then explore how "talk" and "activity" are key gendered features of children's relationships with their sisters and brothers, revealing versions of femininity and masculinity, and interplays of power. Finally, we consider how these gendered features of sibling practices have implications for children's ability to deal with change in relationships with their sisters and brothers, especially living apart from each other, and we return to class as a feature of their understandings.