San Lorenzo (, ; Spanish for "Saint Lawrence") is a town and municipality of Puerto Rico located in the eastern central region, north of Patillas and Yabucoa; south of Gurabo; east of Caguas and Cayey; and west of Juncos and Las Piedras. San Lorenzo is spread over twelve barrios and San Lorenzo Pueblo (the downtown area and the administrative center of the city). It is part of the San Juan-Caguas-Guaynabo Metropolitan Statistical Area.
San Lorenzo is called "The town of the Samaritans" and "Land of Legends." The patron of the municipality is Nuestra Señora de las Mercedes (Our Lady of Mercedes). The surrounding areas produce tobacco and sugar cane.
San Lorenzo was founded in 1737 under the name San Miguel de Hato Grande by Valeriano Muñoz de Oneca from Seville, Spain. The original settlers of the then village were the Muñoz de Oneca, López de Alicea, and Sánchez de Cos families. The church was erected in 1811.
Hurricane Maria on September 20, 2017 triggered numerous landslides in San Lorenzo with the significant amount of rainfall.
