The first annual meeting of the Pioneer Total Abstinence Association took place 100 years ago tomorrow. Although membership is less than a third of what it was 50 years ago, with 160,000 members the association ranks as one of Ireland's largest voluntary organisations. And it is holding its own, having experienced no significant drop in numbers over the past five years, with an annual intake of around 10,000 new members.

This might seem surprising in view of mounting concern at underage drinking. At the beginning of the year, the Minister for Health and Children, Micheβl Martin, announced a campaign to tackle this serious social issue. And at the sixth annual conference of the Irish Association of Suicidology, which was held in Cork earlier in the year, Carol Fitzpatrick, who is professor of child psychiatry at University College, Dublin, expressed concern at the trend, which she said Ireland would have to address if it is serious about preventing suicide.

The PTAA is attempting to counter the attractions of the pub culture for the young. Brenda Lynch (25), from Blanchardstown in Dublin, joined the Young Pioneers after her Confirmation, with a number of her classmates.

Her local pioneer centre was organising regular events and she went along. She became more involved in the organisation and, when the National Youth Committee was formed in 1997, she was elected its Dublin representative. She is now chairwoman of the Young Pioneers.

She joined because many of her friends did. "The reason I stayed a pioneer was because I believe the PTAA has something to offer me and other young people. Being a pioneer is part of what I am now," she says. "It means being part of an organisation which can offer people a choice and support them in that choice - not to drink alcohol or take drugs."

But there is a lot more to being a pioneer than not drinking alcohol, according to Lynch. The Young Pioneers organise a range of local events, such as discos, quizzes and sports. There are two national youth seminars a year, an all-Ireland sports competition and a national pioneer ball.

They also have a school-visiting programme to provide young people with information about alcohol and drugs and tell them what the association is about. In fact, there have been more requests for school visits in the past year than in the previous 10, because of concerns about underage drinking, according to Father Bernard McGuckian SJ, the association's central director.

He says the pioneer movement was "one of the most unlikely movements in a mainstream religion in the 20th century". The association was founded by Father James Cullen SJ in December 1898, in St Francis Xavier's Church, on Gardiner Street in Dublin.

His motivation was the heartbreak he had seen alcohol cause in so many homes. Initially, he intended to admit only women, because of his conviction that "women have ever been, by word and example, the world's greatest social reformers", and also because "they were the greatest sufferers in the wreckage caused by drink". "In fighting for temperance," he said, "they would be fighting, as no other could fight, for themselves and for their children, for earth and for heaven." But he was persuaded to allow men to join.

The temperance movement is a relatively recent phenomenon, a product of the 18th-century Enlightenment. It first gained ground among Quakers, Methodists and Presbyterians. Indeed, it was a Quaker friend who persuaded the great temperance priest Father Theobald Mathew, of Cork, to "take the pledge" in 1838, so enabling the movement to make headway in Irish Catholicism.

Father Mathew's crusade barely survived the Famine, but it inspired Father Cullen to mobilise the potential for idealism it revealed.

He saw devotion to the Sacred Heart, "the dominant Catholic spirituality of the time", as Father McGuckian describes it, as a "more vigorous and sensitive medium through which to advocate abstention" than merely administering the pledge.

Father Cullen was "a real Napoleon for organisation", according to Father McGuckian, and the association grew at an astonishing pace. By the end of the first World War it numbered 200,000, growing to 500,000 by the end of the second World War. In the meantime, its silver -jubilee celebrations brought 15,000 people to the RDS, in Dublin , in 1924.

After 1942, its annual rally became one of the highlights of Dublin's religious year - two large theatres were filled to overflowing, and those who attended said it was difficult to convey the enthusiasm and excitement the gatherings generated.

After the second World War, with large-scale Irish emigration, pioneer centres were set up in Britain, the United States and Australia. By the end of the 1950s, worldwide membership was 500,000. But emigration caused membership numbers in Ireland to even out and then decline slightly. Still, a remarkable 115,000 attended the mammoth diamond-jubilee celebrations in Croke Park, in 1959.

During the 1960s there was a marked growth in membership in recently formed African countries such as Nigeria, Kenya and Zambia.

A new questioning spirit was part of the culture of the late 1960s. After the second Vatican Council, traditional organisations were scrutinised for their continuing relevance. New membership in Ireland had been increasing up to December 1967, but thereafter a steep decline set in. Nevertheless, the 75th anniversary pilgrimage to Knock shrine in Co Mayo saw an attendance of about 60,000 - the largest pilgrimage at Knock, according to the late Mgr James Horan.

In the early 1970s, the association turned its attention to the relatively new phenomenon of drinking among teenagers. In 1972, it set up Renewal Action and Youth (RAY), whose members committed themselves to total abstinence until they were 18, but the dramatic changes in Irish social life in the 1990s required a different approach. By then, drug abuse had become a major concern to Irish parents.

Young Pioneers replaced RAY in 1995; as well as pledging to abstain from alcohol until at least 18, members promised to "stay away from drugs for life".

A survey in 1993-94 revealed that 8 per cent of all adults were pioneers, of whom there was a slightly higher percentage of women; the highest percentage of members was in the over-50 age group; farmers were the single largest occupational group; rural membership was more than twice that in urban areas; and Connacht-Ulster had the highest percentage of pioneers - more than three times that of Dublin.

The Irish association maintains close contact with the growing number of pioneers in Africa, Australia, New Zealand, the Pacific and North America. Father McGuckian is convinced that although the association was a predominantly Irish movement of the 20th century, it will be stronger in other parts of the world in the century ahead.

The Pioneer Total Abstinence Association is holding a concert at the National Concert Hall, Dublin, on October 21st; proceeds will go to help victims of the attacks on New York and Washington DC (bookings on 01-4170000)