Park Slope is a neighborhood in South Brooklyn, New York City, within the area once known as South Brooklyn. Park Slope is roughly bounded by Prospect Park and Prospect Park West to the east, Fourth Avenue to the west, Flatbush Avenue to the north, and Prospect Expressway to the south. Generally, the neighborhood is divided into three sections from north to south: North Slope, Center Slope, and South Slope. The neighborhood takes its name from its location on the western slope of neighboring Prospect Park. Fifth Avenue and Seventh Avenue are its primary commercial streets, while its east–west side streets are lined with brownstones and apartment buildings.

Park Slope was settled by the Lenape before Europeans arrived in the 17th century. The area was mostly farms and woods until the early 19th century, when the land was subdivided into rectangular parcels. The western section of the neighborhood was occupied in the mid-19th century, being located near the industrial Gowanus Canal and ferries. After the completion of Prospect Park, numerous mansions and rowhouses were developed in Park Slope's eastern section in the 1880s. Park Slope faced social and infrastructural decline in the mid-20th century, but the building stock was renovated after the area became gentrified starting in the 1960s. Much of the neighborhood is overlaid by the Park Slope Historic District, which is composed of a National Historic District and a New York City landmark district.

Park Slope features historic buildings, top-rated restaurants, bars, and shops, as well as proximity to Prospect Park, the Brooklyn Academy of Music, the Brooklyn Botanic Garden, the Brooklyn Museum, the Brooklyn Conservatory of Music, and the Central Library and Park Slope branches of the Brooklyn Public Library. The neighborhood had a population of about 62,200 as of the 2000 census. Park Slope is generally ranked as one of New York City's most desirable neighborhoods.

Park Slope is part of Brooklyn Community District 6, and its primary ZIP Codes are 11215 and 11217. It is patrolled by the 78th Precinct of the New York City Police Department. Politically, it is represented by the New York City Council's 33rd and 39th Districts.

Though modern-day Brooklyn is coextensive with Kings County, this was not always the case. South Brooklyn, an area in central Kings County extending to the former Brooklyn city line near Green-Wood Cemetery's southern border, was originally settled by the Canarsee Indians, one of several indigenous Lenape peoples who farmed and hunted on the land. The Lenape typically lived in wigwams, and had larger fishing and hunting communities near freshwater sites on higher land. Several Lenape roads crossed the landscape and were later widened into "ferry roads" by 17th-century Dutch settlers, since they were used to provide transport to the waterfront. One was the Flatbush Road, running roughly north–south to the east of the path of present-day Flatbush Avenue. Just north of modern-day Park Slope was the Jamaica Road, running east to Jamaica, Queens, on what is now the path of Fulton Street.

The first European settlement occurred in 1637-1639 when Willem Kieft, the Dutch West India Company's director, purchased almost all land in what is now Brooklyn and Queens. The area was used as farmland over the next two centuries.

During the American Revolutionary War, on August 27, 1776, the Park Slope area served as the backdrop for the beginning of the Battle of Long Island. In this battle, over 10,000 British soldiers and Hessian mercenaries routed outnumbered American forces, which resulted in the British occupation of Long and Staten Islands. The Battle Pass site is now preserved in Prospect Park, while on Fifth Avenue, there is a reconstruction of the Old Stone House, a farmhouse where a countercharge covered the American retreat.

Transit from Park Slope improved in the early 19th century. The Brooklyn, Jamaica and Flatbush Turnpike Company was incorporated in 1809 to widen the Flatbush and Jamaica ferry roads, prior to the establishment of the Fulton Ferry to Manhattan in 1814. Afterward, stagecoaches started running on Flatbush Road in 1830, with omnibus service following four years later. The land comprising what is now Park Slope was still mostly undeveloped c. 1810. There were a couple of houses on and around Prospect Hill, a tavern, and a resort; the section of Flatbush Road through present-day Prospect Park contained ponds of standing water, which caused fevers and other illnesses. Soon afterward, the land was split up into rectangular parcels, which were bought by numerous people and cultivated as farmland. As in the rest of Kings County, the farmland was likely dependent on slave labor.