Adlington represented Great Britain in the 2008 Summer Olympics, competing in the 400-metre freestyle and 800-metre freestyle events. She was also scheduled to swim in the 4×200-metre freestyle relay but was rested in the heat and the team failed to qualify for the final. In the heats of the 400-metre freestyle, she broke the Commonwealth record with a time of 4:02.24. On 11 August 2008, she won an Olympic gold medal in the same event, with a time of 4:03.22, overtaking Katie Hoff of the United States in the last 20 metres. She was the first woman to win swimming gold for Great Britain since Anita Lonsbrough in 1960. She was the first British swimmer to win more than one gold medal at a single Olympic Games since Henry Taylor won three in 1908.