This chapter describes the fetal period, and explains the importance of the fetal period in human development. It provides examples of structures that were established during the embryonic period, but come to functional maturity during the fetal period. Many significant developments occur during the fetal period. The major processes during the fetal period are growth and differentiation of established structures. Differential growth of the fetus is shown by the dramatic morphogenetic changes that occur. The beginnings of the kidneys can be seen in the fifth-week embryo, but it is during the fetal period that the nephrons are formed. The chapter explores the change in the relative size of the head during the fetal period. Vernix caseosa and lanugo are present on the fetal skin by the end of the early fetal period and persist until about term. The characteristics enumerated for the fetal period are primarily external characteristics and particularly reflective of morphogenesis.