Añasco (Spanish pronunciation: [aˈɲasko]), named after one of its settlers, Don Luis de Añasco, is a municipality of Puerto Rico located on the west coast of the island bordering the Mona Passage to the west, north of Mayagüez, and Las Marias; south of Rincón, Aguada, and Moca and west of San Sebastián and Las Marias. It is part of the Aguadilla-Isabela-San Sebastián Metropolitan Statistical Area.

The town was founded on October 18, 1733 and named after Don Luis de Añasco, a colonist from the Extremadura region of Spain who came to Puerto Rico with Juan Ponce de León. Añasco was founded by the initiative of rich landowner Don José de Santiago, who wanted to establish the "villa" in properties owned by Don Luis de Añasco. The property was located on the margins of the río "Guaorabo", as the Taínos called it.

Anasco town was proceeded by the first settlement of San German.In Novermber 1511, Juan Ponce de Leon handed over governorship to Juan Ceron, a lieutenant of the viceroy Diego Colon (son of Cristobal Colon or Cristopher Columbus).Ceron ordered Miguel de Toro, a lieutenant of Juan Ponce de Leon, to create a "Christian Village" in western Borinquen, calling it San German. This was the second attempt of foundation given in 1511 at the mouth of the Guaorabo River (present day Rio Anasco), near the area known today as Anasco, Puerto Rico. This first settlement was attacked in 1528, 1538, and again in 1554. A fort to protect this town began in 1540, but its construction was suspended in 1546 when the people decided to move inland being tired of attacks. Attacks by Carib Indians forced the population to move south inland to the present site of the present town of San German.