Infants and children. Infancy: birth to six months -- Toddlers: six months to two years -- Preschool: two to five years -- School age: six to twelve years -- Teens and adults. Adolescence: thirteen to nineteen years -- Young adult: nineteen to thirty-five years -- Middle adult: thirty-six to sixty-five years -- Older adult: sixty-six years and older -- Resources -- Personal information file -- Summary of selected legislation.