Testicular volume ≥4ml and appearance of breast budding are the first signs of puberty. Delayed puberty is diagnosed in the absence of thelarche by 13 y or menarche by 15 y in girls and absence of testicular enlargement by 14 y in boys. Delayed puberty can be due to hypogonadotrophic hypogonadism, hypergonadotrophic hypogonadism or eugonadotrophic eugonadism characterised by low, elevated and normal gonadotrophin levels, respectively. Constitutional Delay of Growth and Puberty (CDGP) and systemic illness should be considered before pathological causes. Assessment of sexual maturity by Tanner's staging and anthropometric assessment on growth chart is pivotal. Lack of menarche in girls with thelarche suggests structural abnormalities of reproductive tract or disorders of sexual development. Measurement of bone age helps to interpret hormone measurements and decide on timing of pubertal induction. Ultrasound assessment of abdomen gives valuable clues to pubertal onset (in girls) and possible underlying etiology. Karyotyping is mandatory in all girls with delayed puberty and short stature, and delayed menarche and boys with hypergonadotrophic hypogonadism. Gonadotrophin releasing hormone analogue stimulation test may help distinguish hypogonadotrophic hypogonadism from CDGP. Pubertal induction is done with intramuscular testosterone and oral estradiol in boys and girls, respectively. Hormone replacement is begun at low doses and slowly escalated over 2 y to mimic a physiological puberty process. Short course of testosterone for 3 to 6 mo is helpful in adolescent boys with CDGP and psychological distress. Attainment of adult sexual maturity by 18 y is mandatory to rule out disorders of hypothalamic pituitary gonadal axis.