1985: Born April 1 in Johannesburg, South Africa.
1994-96: Member of Great Britain under-12 squad.
1999: Takes third in the all-around and first in floor exercise at British Junior Championships.
2000: Finishes second on uneven bars at Hungarian International. Wins all-around gold at the Junior Commonwealth Games in Scotland. Finishes 14th in all-around and sixth on uneven bars at Junior European Championships in Paris. At British Junior Championships she takes third place in all-around and first on uneven bars. Also first on floor exercise.
2001: At senior World Championships in Ghent, Tweddle finishes 24th in all-around and ninth with team. Secures first place at British Championships on both all-around and uneven bars. Takes seventh place on balance beam at Cottbus Cup in Germany, and first on uneven bars in Great Britain v Romania international match.
2002: Finishes first on uneven bars at Cottbus Cup. Becomes overall British champion for second straight year - winning on uneven bars and beam, while taking bronze in vault and fourth on floor.
July 27 - Wins silver as member of women's team at Commonwealth Games.
July 29 - Takes gold in women's uneven bars at Commonwealth Games.
2003: Becomes first British gymnast to win a medal at World Championships, claiming bronze on uneven bars.
2004: Wins silver medal at European Championships on uneven bars and finishes fifth with Great Britain team. Finishes 19th in all-around competition at Athens Olympic Games and 11th in team competition with Team GB. Wins silver medal on uneven bars and finishes fifth in floor competition at World Cup finals in Birmingham.
2006: Forced to withdraw from Commonwealth Games in Melbourne after sustaining ankle injury in training. Becomes first British gymnast to win European Championship gold, taking gold on the uneven bars.
October - Becomes Britain's first ever gymnastics world champion when she wins on the uneven bars.
Wins gold again on the uneven bars at the World Cup final.
2007: Helps Great Britain secure a team place in the Beijing Olympics at the World Championships. Wins seventh successive British National Championships title.
2008: Wins silver medal on the floor exercise and places fourth on uneven bars at European Championships. Finishes fourth in the uneven bars final at the Beijing Olympics.
2009: Wins double gold at the European Championships on the floor and bars. Wins gold in the World Championships floor final held in London but fails to qualify for the bars final.
2010: Retains her European floor and bars titles and helps the British team to a silver in the team all-around competition. Becomes a three-time world champion after winning gold on the uneven bars at the World Championships in Rotterdam but fails to make the floor final. Appointed a Member of the Order of the British Empire (MBE) in the New Year Honours list.
2011: Wins European gold for the sixth time when she takes the uneven bars title in Berlin.
2012: April - Ruled out of the European Championships following minor keyhole surgery to her knee.
June - Wins gold on the uneven bars in the Olympic trial events at Pipers Vale, Ipswich, and in Liverpool.
August 6 - Wins Olympic bronze in the uneven bars.
December 18 - Announced as a contestant on ITV1's Dancing on Ice.
2013: March - Crowned Dancing on Ice champion and then takes part in a spin-off tour.
May - Rules herself out of competing at the 2016 Rio Olympics, saying they are "one step too far".
August 6 - Retires from competitive gymnastics, a year on from her Olympic triumph.