Adelaide City Football Club is a semi-professional soccer club based in Oakden, a north-eastern suburb of Adelaide. The club was a founding member of the now-defunct National Soccer League (NSL) and currently competes in the National Premier Leagues South Australia (NPL SA).

The club was founded in 1946 by Adelaide's Italian community, who named the club Juventus. Adelaide City was one of 14 founding members of the National Soccer League in 1977 and competed concurrently in every edition of the competition before withdrawing a few weeks before the beginning of the league's final season. The club is one of Australia's most successful, their first major silverware coming in 1979 when they defeated St George in the NSL Cup final. Under legendary manager Zoran Matić, they won three National Soccer League titles in 1986, 1992 and 1994, alongside two further cup wins in 1989 and 1992. The club also became the first Australian representative to win a continental title, when they defeated Mount Wellington on penalties in the 1987 Oceania Club Championship final. City is also the most successful club in South Australian competitions, winning 19 first-division titles and 18 Federation Cups, including five in a row from 1969 until 1973. The club reached the quarter-finals of the inaugural FFA Cup, which included a 1–0 over A-League side and reigning AFC Champions League champions, Western Sydney Wanderers, in the round of 32, becoming the first member federation club to defeat an A-League club in the competition.

Adelaide City has historically been one of the most prolific producers of players selected for the Australian national team, with the club providing the third most Socceroos of any NSL club behind Marconi and South Melbourne; notable Adelaide City players who have gone on to represent Australia include John and Ross Aloisi, Aurelio and Tony Vidmar, Sergio Melta, John Perin, Milan Ivanović, Bugsy Nyskohus and Alex Tobin. Former City NSL striker and current coach Damian Mori holds the record for the most goals scored in the national domestic league with 240 – 131 of which were scored in City colours. Tobin holds the record for playing the most senior games in Australian domestic competition with 522, including 436 for City.

The club was founded in a back room of the Bailetti sports store on Hindley Street, Adelaide by the shop's owner Mario Bailetti and a small group of former members of a club called Savoia. Supported primarily by members of the city's Italian community, the club was originally called Juventus after the Italian club in 1946 and subsequently renamed Adelaide Juventus in 1960. Bailetti served as chairman for the first 14 years of the club's existence and, after also serving in senior executive roles with the South Australian Soccer Federation, later had the western grandstand of Hindmarsh Stadium named in his honour.

Juventus began life in the second division of South Australian soccer, winning promotion at its first attempt. However, Juventus was relegated straight back to the second tier in 1947, where it remained for another two years. In 1949, Juventus was promoted again and it has remained at the highest level of South Australian soccer ever since, save for several seasons during the club's National Soccer League stint. Early star players included Italian post-war migrant Fulvio Pagani, a fullback who was also selected for the Australian national team.

The first of many state championships arrived in 1953. This was followed by another five titles before the end of the 1950s including an unprecedented four in-a-row between 1956 and 1959. Between 1953 and 1959, the club won 106 of 127 games and six of the seven championships it contested. An additional three South Australian championships were won in the 1960s and three more titles were won in the 1970s up until 1976. The club's original home was Kensington Oval, Adelaide, then known as Olympic Sports Field.

During the club's formative years, there were already signs of its potential on the national stage. Adelaide Juventus competed in the inaugural Australia Cup in 1962, finishing third in the national knockout tournament. Its cup run produced wins over eventual national league rivals, Brisbane Azzurri and Sydney Hakoah, before it was denied a place in the final courtesy of a 3–0 loss to St George Budapest in front of 5000 spectators at Hindmarsh Stadium. Juventus reached the semi-finals of the Australia Cup again in 1963, this time having its final hopes dashed by eventual champion Port Melbourne Slavia. The club competed in all but the last edition of the tournament in 1968 but never again progressed beyond the quarter-finals.

In 1977, the club renamed itself Adelaide City and became a founding member of the inaugural NSL competition; Australia's first national league of any football code. The team was captained by Frank Lister, who was later inducted into the South Australian Soccer Hall of Fame in 2004. The club's inaugural NSL coach was Edmund Kreft. Roger Romanowicz, Ron Fraser, Fred Yung, Zoran Matić, Lister, John Perin, David Leane, Sergio Melta, Brian Northcote, John Nyskohus and Gary Marocchi started for the Black and Whites in their first-ever national league clash, a 0–0 draw against the Brisbane Lions at Olympic Sports Field, watched by 6320 people.