Friendship occupies an important place in the growing body of literature in child development and gerontological research. As such, it may be useful for researchers from both fields to consider what can be learned from work carried out in each tradition. Therefore, we present a selected review of topics in friendship research across the life span. Through discussion of the value of friendship, the development of friendship, challenges to friendship, the gendered nature of friendship, and the connection between friends and family, points of commonality and contrast are identified. We conclude by presenting possible avenues for future investigation for researchers interested in friendship at any point in the life span.