The disorders of skin pigmentation discussed in this chapter fall into two categories: disorders of hyperpigmentation (melasma, postinflammatory hyperpigmentation, drug-induced hyperpigmentation, erythema dyschromicum perstans, lentigines, confluent and reticulated papillomatosis of Gougerot and Carteaud, and Dowling-Degos disease) and disorders of hypopigmentation (vitiligo, albinism, piebaldism, and idiopathic guttate hypomelanosis). The definition, epidemiology, etiology and pathogenesis, diagnosis, differential diagnosis, and treatment are discussed for each condition. Figures show examples of melasma, hyperpigmentation secondary to acne, vitiligo and its response to treatment with tacrolimus and with narrow-band ultraviolet B (UVB) light, Vogt-Koyanagi-Harada syndrome, and piebaldism. A table lists therapeutic approaches to vitiligo. This chapter contains 182 references.