Juana Díaz (Spanish pronunciation: [ˈxwana ˈði.as]) is a municipality of Puerto Rico (U.S.) located in the southern coast of the island, south of Jayuya, Ciales, Orocovis and Villalba; east of Ponce; and west of Coamo and Santa Isabel and the Caribbean Sea to the south. Juana Díaz is spread over 13 wards and Juana Diaz Pueblo (the downtown area and the administrative center of the city). It is part of the Ponce Metropolitan Statistical Area.
Juana Díaz is known as "La Ciudad del Mabí" (Mabí City). Mabi is a fermented Taíno beverage made out from the bark of the mabi tree Colubrina elliptica.
Juana Díaz was founded in 1798 and was known as Ciudad de Jacagua, in honor of the Taíno Cacique Jacaguax. The civil government of this territory was established on April 25, 1798.
In 1899, Juana Díaz had a population of 27,896.
Juana Díaz is located on the southern coast. Several rivers run through the Juana Díaz territory, among them, Río Inabón and the Río Jacaguas, from which Juana Díaz takes its nickname, "Ciudad del Jacaguas". The Guayabal dam between Juana Díaz and Villalba is located in this river. Among its main tributaries are Río Toa Vaca in Villalba, also dammed.