The Liberal Democrats, and their Liberal predecessors, have seen their fortunes rise and fall through a series of splits and re-alignments in British politics.
Mr Kennedy took over the Lib Dems from Paddy Ashdown
As a political philosophy, Liberalism grew up around a belief in the rights of the individual and freedom of choice.
This has developed into a modern political movement which gives the state an important role in achieving equal opportunities and ending poverty and discrimination.
The party grew out of the political upheaval in 1832, when the power of the mainly aristocratic Whigs was increasingly challenged by "liberals" and "radicals".
A split in the ranks of the Tories brought more converts, and what became known as the Liberal Party emerged in the middle of the 19th Century.
After the election of 1868, William Gladstone formed the government that established the Liberals as a parliamentary force.
Despite a split over the issue of Home Rule for Ireland in 1886, the Liberals continued to vie for power with the Conservatives until the First World War. In peacetime, however, splits in Liberal ranks helped a rapidly-growing Labour Party to become the official Opposition.
In the wilderness
Over the next 40 years, the Liberal vote shrank and by the 1950s, the Liberal vote had declined to just 2.5%, and there was talk of a merger with the Tories.
In the 1960s, the handful of Liberal MPs led to a jibe that the entire parliamentary party could travel to the Commons in a single taxi.
But under Jo Grimmond, the Liberals began to rebuild at the grassroots, with a focus on community issues and what became known as "pavement politics".
By winning local council seats, party activists established a power base in cities like Liverpool, and success in local government revitalised their national ambitions.
A sniff of power
Although their numbers at Westminster were still small, the close result in the February 1974 election led Prime Minister Edward Heath to invite the Liberals to join a coalition to keep the Conservatives in office.
The offer was rejected by the Liberal leader, Jeremy Thorpe, who might have become home secretary. Instead, Labour took power, and the Liberals were back on the fringes.
Mr Thorpe resigned the leadership over accusations of an affair with a male model, Norman Scott.
After a police investigation, Mr Thorpe found himself in the dock at the Old Bailey, charged with conspiring to murder Scott. He was acquitted, but his political career was already in ruins, and he lost his seat at the 1979 election.
Under Mr Thorpe's leadership the Liberals enjoyed a boost in popularity
Under Mr Thorpe's leadership, the Liberals had increased their support at the general election from two million to six million, gaining almost 20% of the popular vote.
The party's new leader, David Steel, was able to capitalise on this growing influence by entering into the "Lib-Lab pact" and for a time supported Jim Callaghan's minority Labour government.
The political landscape changed after Labour's defeat in 1979.
Four ex-ministers, the "gang of four", left to form the Social Democratic Party. The Liberals entered into an Alliance with the SDP, and in 1983, this strategy saw the two parties capture 25% of the popular vote though very few seats.
The Liberals never quite achieved the promised breakthrough at the ballot box. The optimism of party leader David Steel, when he urged conference delegates to "go back to your constituencies and prepare for government", was never realised.
In 1988, the Liberals formally merged with the SDP, eventually settling on the name Liberal Democrats. Under a new leader, Paddy Ashdown, the party tried to present itself as a distinctive political force, separate from both Labour and the Conservatives, and pursuing radical policies.
Mr Ashdown is pictured with former Liberal leader David Steel
After a disappointing start, the new party began to pick up support during the early 1990s. The Liberal tradition of capturing parliamentary seats at by-elections was successfully revived.
By 1997 the Lib Dems had become the second-largest party in local elections, controlling 55 councils and pushing the Tories into third place.
At the 1997 election, the Lib Dems wooed voters by arguing that their policies would "make a difference". The party promised to put a penny on income tax to fund improvements in education, and placed considerable emphasis on environmental issues.
Resources were carefully targeted on winnable - mainly Tory - seats, and the strategy paid off. To the surprise of some commentators, the Lib Dems returned to Westminster with 46 seats.
Under Paddy Ashdown's leadership, the Lib Dems began to co-operate with Labour in developing policies in areas where they had common goals, such as the commitment to devolution.
But the relationship cooled under Charles Kennedy perhaps because of Labour's seeming lack of enthusiasm for reforming the voting system, long the objective of the third party.
The social policies of the Liberal Democrats have placed the party on the centre-left, in territory also occupied by New Labour.
But whatever overtures may have been made by the Conservatives in the past, Mr Kennedy made it clear early on that his party sees no future with the Tories.
While still closer to Labour than the Tories, the Lib Dems have not been slow to criticise government policies - most notably over the Iraq war.
The Liberal Democrats believe that their vision of a "radical centre" in British politics should translate into government action to promote social justice, and a commitment to provide greater protection for the environment.
Old Liberal campaigns continue, with calls for constitutional change, particularly reform of the electoral system to end what is seen as the institutional bias towards two-party politics.
In the 2001 election the Lib Dems won 52 seats and subsequently have managed to increase that to 55 in a series of by-election successes.
Mr Kennedy will be hoping to capitalise on his opposition to the Iraq war to win over traditional Labour supporters disheartened by the direction Tony Blair has taken New Labour, and he will be hoping to pick up pro-European Tory votes.