The New Democratic Party of Prince Edward Island (NDP PEI) is a social democratic political party in Prince Edward Island, Canada. It is a provincial section of the federal New Democratic Party (NDP).

The NDP's predecessor, the Co-operative Commonwealth Federation (CCF), began in 1936 when a CCF club was founded in the Bedeque region during a visit by CCF MP Ted Garland. But the Island CCF did not run candidates until 1943 when the national party made a concerted effort to rally the party by sending an organizer to recruit several candidates to run in the 1943 provincial election. Later that year, a founding convention was held with York South MP Joseph Noseworthy as guest speaker. Irving Toombs was elected president and Douglas MacFarlane provincial secretary.

The CCF ran candidates on the Island in the 1945 federal election, for the first time federally, and again in a provincial by-election in December. In the 1947 provincial election, the CCF contested 16 seats. The party only contested five seats in the 1951 election, however, due to bad road conditions and high deposits. The CCF's candidate that year in 3rd Prince, Hilda Ramsay, became the first woman ever to run in a PEI provincial election.

While not contesting any further provincial elections, the CCF ran one candidate in PEI in the 1953 federal election, three in the 1957 federal election and one in 1958.

The NDP PEI was founded at a convention in Charlottetown on November 25, 1961, three months after the founding of the New Democratic Party of Canada. Federal leader Tommy Douglas addressed the meeting and Ian Webster was elected provincial president and Lorne Perry vice president. The NDP went on to stand a full slate of four candidates in PEI during the 1962 federal election and, thereafter, ran full slates on the island during federal elections.

The 1968 federal election saw Charlottetown teacher David Hall in Hillsborough make the party's strongest showing. He was subsequently chosen as the PEI NDP's first provincial leader. The party contested three provincial by-elections in 1972, its first attempt at provincial seats since the CCF days, and received 5.2 per cent of the total vote. Aquinas Ryan, a school principal from Morell in Kings County, led the party into the 1974 provincial general election and got 5.9% of the vote, but due to internal bickering, the party fell in the polls.

In the 1993 election, under the leadership of Larry Duchesne, the party share of the popular vote rose to 5.4%. Dr. Herb Dickieson took over as leader, and changed the name of the party from the PEI NDP, to the "Island New Democrats". In the 1996 election, the party captured 7.8% of the vote, and Dr. Dickieson was elected to the Legislative Assembly of Prince Edward Island for the riding of West Point-Bloomfield. He was the first member of a third party to ever win a seat to the PEI Legislative Assembly. Dr. Dickieson narrowly lost his seat in the 2000 election despite the party's overall popular vote rising to 8.4%.

During the 2003 provincial election, the party lacked funds and were poorly organized. The party lost its base of support, only capturing 3% of the popular vote. Some within the party credit this to the return to the Liberal Party of Prince Edward Island of many voters who left the party following the Liberal provincial government's decision to reduce wages of all public employees by 7.5% in the early 1990s. The budget for the 2003 election was estimated to be around $30,000, compared to nearly $1 million for each of the other parties.