Theses have been written about it. Speeches have been made world-wide about it, but still it remains a mystery: why don't more women run in elections? It's a question pertinent even when circumstances are highly favourable to women - even at UCD, in a college where almost half the students are women and where women are highly active at various levels within the Student's Union, when it comes to the elections for the Union's four top posts, women simply don't run.

Stranger still, the number of women candidates contesting the top jobs has gone down, not up, in recent years. In the 1980s and early 1990s there would be at least one woman, possibly more, among every year's four elected sabbatical or executive officers. Sabbatical officers take a year out of college while holding office. Yet in 1998, of the candidates who ran for the Students Union sabbatical offices, three of the four races - for president, welfare and education officers - were exclusively male.

Only in the election of an entertainments officer did a woman choose to contest an office, unsuccessfully. The result is that this year, like last year, all the elected officers are male.

It is a phenomenon that puzzles the outgoing Students' Union president, Ian Walsh, who has just finished his year-long term. "I can't really answer the question as to why women don't actually run," he says. "There is not much evidence to say that students don't vote for a female candidate," he says. "Since I have been in college I can think of a number of female candidates. Some of them were elected, some weren't. The person who came across as the best candidate generally did win the election. I can't think of instances where I thought a female superior in terms of capabilities was beaten by a male who was obviously inferior."

A glance at the results of elections to the Students Council, its parliament, also knocks on the head the idea that women candidates in UCD face discrimination.

Women have about half the seats on the council, the sort of result that would be a dream come true for feminists if repeated in the Dail.

Furthermore, many of the big explanations proffered to explain why women don't enter national politics simply don't apply at UCD. While the political parties, particularly Fianna Fail, have increasingly played a role in college elections, they don't control the selection of candidates. Any female student would have little problem if they wanted to get on a ballot paper. Nor do women student candidates face the kind of family commitments that often make it difficult for women to run in national campaigns. On top of that, young people in general are more gender-neutral than is the case among many older voters. So on paper at least, woman student candidates face a far more level playing-pitch than woman candidates in national politics.

So, why don't women run for the top union jobs? One unsuccessful candidate, Jennifer English, knocks on the head the myth that "rougher" sabbatical elections are intimidating to women. "I never found that," she says with a laugh - and indeed, by the standards of the campaigns of the 1980s, today's sabbatical campaigns - for male and female candidates alike - are pretty tame affairs, as one-time UCD Students' Union candidate, Mags Glennon, confirms.

Glennon, now employed full-time at DCU, points out that students in general, male and female, are much less involved in student politics and college societies than in her day, a view shared by Ian Walsh. Still, the college societies and political parties can get women to run for their top jobs - unlike the union.

Walsh has another theory: "Maybe there is a greater academic ethic among female students than there is among male students. There is a greater tendency among male students to think they are in a position to doss off for a year, take a year off." That suggestion certainly ties in with studies that show girls in school push themselves more and are more academically minded than boys.

Jennifer English does make the point that women aren't specifically encouraged to run, a point Walsh concedes. So, should women in UCD be given some sort of positive discrimination in union elections? Walsh says: "I am broadly in favour of that sort of initiative but it is obviously easier in a multi-seat constituency. But all of these sabbatical elections are one-seat constituencies. I do think it would be bringing positive discrimination too far to say that next year the president has to be female, the year after it can be male."

Whatever the reason, in the country's largest college, probably the place where women are least likely to run into gender stereotyping and where there are fewer barriers preventing a woman from running for election than in Irish politics generally, women still aren't running for election to the top posts. The most logical explanation is simply that women are choosing not to run. If they are choosing not to run in an electorate as woman-friendly or at least gender-neutral as UCD, that may well explain why so few women run in national politics - with the blame lying as much with women opting out as with sexist men and sexist voters blocking them.