The Philadelphia nativist riots were a series of riots that took place on May 6—8 and July 6—7, 1844, in Philadelphia, Pennsylvania, United States and the adjacent districts of Kensington and Southwark. The riots were a result of rising anti-Catholic sentiment at the growing population of Irish Catholic immigrants. The government brought in over a thousand militia—they confronted the nativist mobs and killed or wounded hundreds of anti-Catholic rioters.

Philadelphia, commonly referred to as Philly, is the most populous city in the U.S. state of Pennsylvania. Philadelphia is the nation's sixth-most populous city, with a population of 1,603,797 in the 2020 census and is the urban core of the larger Delaware Valley, the nation's seventh-largest and one of the world's largest metropolitan regions consisting of 6.245 million residents in the metropolitan statistical area and 7.366 million residents in its combined statistical area. Philadelphia is known for its extensive contributions to United States history, especially the American Revolution, and served as the nation's capital until 1800. It maintains contemporary influence in business and industry, culture, sports, and music.