Prime Minister Tony Blair became Labour leader in 1994 following the death of John Smith and led the party to power in 1997.
Writing for BBC News Online, he says that the party's achievements have always depended on two things: Its members and its values.

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I feel immensely privileged to be leader of the Labour Party in our centenary year. Labour's story over the first 100 years has been one of real achievement.

In government, our party has been responsible for many of the greatest social advances of the last 100 years in Britain including the creation of the National Health Service and the welfare state.

The post-war Attlee administration was the greatest peace-term government of the last century. Its achievements were immense. Its leadership remarkable. It shaped the agenda for a generation in Britain.

Proud role

And even when out of government - which happened too often and for too long in this first 100 years - Labour played a proud role in the great progressive movements from the votes-for-all crusade at home to the battle against apartheid abroad.

I believe Labour's success has rested on two great strengths - its members and its values. It is our members' deep roots in the wider community that have given this party such strong life even when out of government nationally.

It is the enduring values of social justice, tolerance, decency and opportunity for all, which bind the party together and shape the policies so they meet the concerns and ambitions of the country. And it is these same traditional values, applied in modern ways, which guide this new Labour government.

Core values

These values lie behind the introduction of the minimum wage, one of the goals of the Labour Party's founders but which took 100 years to deliver.

They have shaped the New Deal, which has helped cut youth unemployment by over 60% since the election, numeracy and literacy strategies which have led to big improvements in schools and the £40bn extra investment for education and to rebuild and modernise our health service.

And these same values also lie behind the steps we have taken to help deliver lasting economic prosperity by getting the public finances in shape and giving the Bank of England independence.

They have resulted in low inflation, rising living standards and 700,000 more people in work than at the election. We are demonstrating that enterprise and fairness can go hand in hand.

But there remains a great deal more to do. While the founders of the Labour Party would be astonished how much has changed in the world and the opportunities that now exist, they would be horrified, too, at what has not changed.

In Britain, at the start of this new century, children are still living in poverty, seven million people are unable to read and write properly, while unemployment is still too high. And across the world, hundreds of millions of people denied even basic health care or education.

It is for these reasons that I believe if the Labour Party did not exist, it would be as necessary today to invent it as it was in 1900.

I also believe the best way to honour the vision of those who created our party is to renew our determination to work towards the modern, more prosperous and fairer society which was their historic goal a century ago.