The intersections of masculinities and age have attracted relatively little theorizing. This article examines the theoretical implications of young/old age and masculinities by bringing together two bodies of literature (young age and masculinities and old age and masculinities) and two research studies (one with pre-teenage school students in Australia and one with grandfathers in the United Kingdom). We focus on two key themes: caring practices and relations and the divide between physical activity and intellectual pursuits. Drawing on these themes, we show how age allows for gender transgressions and practices of gender equality and how young boys and old men can also uphold a discourse of hegemonic masculinity, despite age-related tensions. We conclude by arguing that a consideration of age has much to offer in terms of thinking about how gender is socially constructed and illuminates the complex power relations of age and gender categories.