January – February – March – April – May – June – July – August – September – October – November – December
- July 1, 1881 - The Municipality of Barceloneta was founded.
- July 1, 1898 - The "Porto Rico Regiment of Infantry, United States Army", later renamed the 65th Infantry Regiment, was created.
- July 1, 1982 - The Nutrition Assistance for Puerto Rico program commenced operations.
- July 1, 1927 - The Municipality of Cataño was founded.
- July 1, 1951 - Birth of Luisito Vigoreaux, actor and producer
- July 4, 1950 - President Harry S. Truman signed Public Act 600, which allowed Puerto Ricans to draft their own constitution establishing the Commonwealth of Puerto Rico.
- July 6, 1987 - Birth of Ricky Sánchez, professional basketball player
- July 9, 1965 - Birth of Anthony Romero, civil rights leader and executive director of the American Civil Liberties Union
- July 15, 1579 - The Municipality of Coamo was founded.
- July 15, 1821 - The Municipality of Nagüabo was founded.
- July 15, 1905 - Birth of Enrique Laguerre, writer and poet (d. 2005)
- July 16, 1918 - Death of José de Diego, statesman, journalist, poet and advocate for Puerto Rico's independence from Spain (b. 1866)
- July 17, 1859 - Birth of Luis Muñoz Rivera, statesman and Resident Commissioner
- July 19, 1760 - The Municipality of Mayagüez was founded.
- July 23, 1967 - The first plebiscite on the political status of Puerto Rico was held, with most supporting the current Commonwealth status.
- July 25, 1840 - The Municipality of Río Grande was founded.
- July 25, 1898 - General Nelson A. Miles lands unopposed in Guánica with the first contingent of American troops during the Spanish–American War.
- July 25, 1952 - The Constitution of Puerto Rico went into effect, and the islands were renamed as the Estado Libre Asociado de Puerto Rico (Commonwealth of Puerto Rico).
- July 25, 1978 - The Cerro Maravilla murders occurred.
- July 26, 1898 - Shortly after the arrival of American troops, the Battle of Yauco occurred.
- July 27, 1857 - Birth of Dr. José Celso Barbosa, founder of Puerto Rico's statehood movement (d. 1921)
- July 30, 1979 - Birth of Carlos Arroyo, professional basketball player
- July 31, 1936 - Pedro Albizu Campos, Juan Antonio Corretjer, Clemente Soto Vélez and other Nationalists were sentenced to federal prison for instigating protests.