The last 2 years of primary school and the first 2 years of secondary school contain an amazing assortment of physical appearances in boys and girls. Whilst some youngsters misleadingly look as if they are 17 and sexually mature, others can almost literally be half their size and still be very much children in all respects. Physically mature 12-year-old girls may have to cope with confusing sexual feelings and experiences for which they privately feel emotionally unready, despite their apparent outward sophistication. Small 14-year-old boys who are late developers suffer agonies wondering if their bodies will ever change into those of men. The sense of being unable to control the body’s physical destiny can bring enormous anxiety, frustration, anger, and distress, as acne takes a hold or breasts become too obvious a feature on a shy girl’s body. This is the age of puberty, which can be protracted or rapid, during which young adolescents reach sexual maturity.