This chapter discusses a range of biological and behavioural traits associated with beaver life history. First the chapter examines their typical daily activity patterns, including time budgets, sex and age-class differences, and activity during winter. Beavers are crepuscular and nocturnal. The time budgets for adult males and females do not differ much for most activities. Beavers adapt to wintertime conditions by becoming less active and live off their pre-prepared food cache and accumulated body fat. It describes a typical beaver family that typically consists of the adult breeding pair with their offspring from the current breeding season and the previous year’s litter. They are living mostly a socially monogamous life, and usually mate for life. The key stages of a beaver’s life cycle are all described, i.e. mate choice and pair bonding, sexual maturity and mating, time of birth and litter sizes, factors affecting reproduction, kit development and life inside beaver lodges, dispersal, mate change, length of pair bonds, and loss of family members and longevity.