The New Puberty examines the phenomenon of girls entering puberty earlier than previous generations and explores what this earlier development can mean physically, emotionally and socially. Louise Greenspan, a pediatric endocrinologist, and Julianna Deardorff, a clinical psychologist specializing in adolescence, combine medical research with psychological and parenting perspectives to create a practical guide for families.

The authors explain that puberty isn't simply a series of physical changes. When a child's physical development occurs significantly ahead of her emotional and cognitive development, it can create difficult situations involving body image, self-esteem, friendships, school, sexuality and social expectations. The book therefore looks at puberty as a biological and psychological transition, rather than simply a medical milestone.

A substantial part of the book investigates possible influences on earlier puberty. The authors discuss factors including body composition, hormone-mimicking chemicals and environmental exposures, nutrition, sleep, and psychological or family stress. They emphasize that early puberty has multiple possible influences rather than one simple cause.

The book is also highly practical. It gives parents, teachers, coaches and other adults guidance on recognizing early developmental changes, communicating with girls about puberty, creating supportive home environments, and knowing when professional medical advice may be appropriate.