This document discusses key transitions and developments that occur during early adulthood between ages 20-40. It covers social changes like following a typical "social clock" of life experiences. Friendships tend to be stronger for women than men. Marriage remains important, though people marry later. Parenting styles like permissive, authoritative, and authoritarian are outlined. Careers are discussed, noting women often have more discontinuous paths. Maintaining work-life balance is important for both employees and employers. Physical abilities peak during early adulthood. Reflections consider applying this knowledge to one's own life path and challenges of early adulthood.