The Eurovision Song Contest 1985 was the 30th edition of the Eurovision Song Contest, held on 4 May 1985 at the Scandinavium in Gothenburg, Sweden, and presented by Lill Lindfors. It was organised by the European Broadcasting Union (EBU) and host broadcaster Sveriges Television (SVT), who staged the event after winning the 1984 contest for Sweden with the song "Diggi-Loo Diggi-Ley" by Herreys. Broadcasters from nineteen countries participated in the contest; Greece and Israel returned after a one-year absence, while the Netherlands and Yugoslavia, which had participated in the previous year's event, declined to enter due to separate memorial events in those countries coinciding with the date of the contest.

The winner was Norway with the song "La det swinge", composed and written by Rolf Løvland and performed by the group Bobbysocks. This was Norway's first contest victory, and only the third top five placing for a country which had placed last on six previous occasions, including three times receiving nul points. With a total of 123 points, "La det swinge" remains the lowest scoring winner under the voting system used between 1975 and 2015. Germany, Sweden, the United Kingdom, and Israel rounded out the top five positions.

The 1985 contest took place in Gothenburg, Sweden, following the country's victory at the 1984 contest with the song "Diggi-Loo Diggi-Ley" performed by Herreys. It was the second time that Sweden had hosted the event, ten years after the 1975 contest was held in Stockholm. The chosen venue was the Scandinavium, an indoor arena inaugurated in 1971, home to the Frölunda HC ice hockey team and the Gothenburg Horse Show. The Scandinavium was chosen by host broadcaster Sveriges Television (SVT) from a number of bids submitted by various Swedish cities and venues; among those known to have been considered to stage the contest were the Berwald Hall in Stockholm and the Tipshallen [sv] in Jönköping. The stadium's maximum capacity of 14,000 people was reduced to 8,000 attendees for the contest, in order to provide space for the stage and technical equipment; this still made it the largest venue and the largest assembled audience in the history of the contest up to that point. During the week leading up to the rehearsals and the televised event, the European Broadcasting Union (EBU) and SVT held an official reception for the participating delegations, which was hosted on the evening of 1 May 1985 at Kronhuset.

Nineteen countries in total participated in the 1985 contest. Greece and Israel both returned following a one-year absence, however the Netherlands and Yugoslavia, which had competed in the previous year's contest, declined to enter in 1985 as the date of the contest coincided with memorial days in the countries, specifically the Remembrance of the Dead, and the anniversary of the death of Yugoslav president Josip Broz Tito, respectively. It was the first time in the contest's history that there was no entry from the Netherlands, with the nation having previously competed in every event since its creation in 1956.

Several of the participating artists in this year's event had previously competed in past editions of the contest. Izhar Cohen, who had previously won the contest for Israel in 1978 with the song "A-Ba-Ni-Bi" alongside the group Alphabeta, made a second appearance for his country at this event. The Danish group Hot Eyes had represented Denmark in 1984, while the Italian duo Al Bano and Romina Power also made a second appearance, having previously competed for Italy in 1976. The two members of group Bobbysocks representing Norway, had competed in the event separately, with Hanne Krogh having represented Norway in 1971, and Elisabeth Andreasson previously competing for Sweden in 1982 as a member of the group Chips alongside Kikki Danielsson; Danielsson also competed in this event as a solo artist for Sweden. The Swiss duo Mariella Farré and Pino Gasparini [de] had also previously competed in the contest for their country with separate entries, with Farré having competed in 1983 as a soloist, while Gasparini had been a member of the Pepe Lienhard Band in 1977. Gary Lux representing Austria as a solo artist, had represented the country in 1983 as a member of the group Westend; and Ireen Sheer, who had already twice competed in Eurovision, for Luxembourg in 1974 and for Germany in 1978, represented Luxembourg again at this contest alongside five other artists. Additionally, Lia Vissi representing Cyprus, had previously participated as backing vocalist at the contest on two separate occasions for Greece in 1979 and 1980, the latter as a member of the group the Epikouri; and Rhonda Heath, who was a member of the group Silver Convention that had represented Germany in 1977, returned as a backing vocalist for Austria at this event.

The Eurovision Song Contest 1985 was produced by SVT. Steen Priwin [sv] served as executive producer and director, Ingemar Wiberg [sv] served as designer, and Curt-Eric Holmquist served as musical director, leading the orchestra. A separate musical director could be nominated by each participating delegation to lead the orchestra during its country's performance, with the host musical director also available to conduct for those countries which did not nominate their own conductor. On behalf of the contest organisers, the EBU, the event was overseen by Frank Naef as scrutineer.

Each participating broadcaster submitted one song, which was required to be no longer than three minutes in duration and performed in the language, or one of the languages, of the country which it represented. A maximum of six performers were allowed on stage during each country's performance. Each entry could utilise all or part of the live orchestra and could use instrumental-only backing tracks, however any backing tracks used could only include the sound of instruments featured on stage being mimed by the performers.

The results of the 1985 contest were determined through the same scoring system as had first been introduced in 1975: each country awarded twelve points to its favourite entry, followed by ten points to its second favourite, and then awarded points in decreasing value from eight to one for the remaining songs which featured in the country's top ten, with countries unable to vote for their own entry. The points awarded by each country were determined by an assembled jury of eleven individuals, who were all required to be members of the public with no connection to the music industry, with a recommendation that there should be a balance between the sexes and that half should be under 25 years old. Each jury member voted in secret and awarded between one and five votes to each participating song, excluding that from their own country and with no abstentions permitted. The votes of each member were collected following the country's performance and then tallied by the non-voting jury chairperson to determine the points to be awarded. In any cases where two or more songs in the top ten received the same number of votes, a show of hands by all jury members was used to determine the final placing.