Some of my best friends are women, but I would not want one of them to marry my sister. Modern-minded members of staff and quite a few students tell me I deserve to be sent to Coventry, if not to Wolverhampton, for daring to preach such gross sexual discrimination. They may be right. It could be that when the sexy sixties have given way to the serious seventies the relations between men and women will be so purely platonic that it will be a matter of no concern whether they are members of the same college or not: or, alternatively, their feelings could have been so completely homogenized that it will make no difference to their emotional relationship whether Julian and Hilary have only one Y-chromosome between them, or two, or none at all. And if this were so my views could be stigmatized as in every way heterodox and deviantly divisive. But I do not believe it. For the foreseeable future at least, men are going to fall in love with women and women find their hearts wooed and won by men. And the fact that this is liable to happen makes a profound difference to our social institutions. In almost every society, marriage and single-sex peer-groups have been found to be satisfactory forms of fife, whereas one needs to be something of an anthropologist to be able to cite societies in which unmarried people of both sexes live together. Colleges conform to this rule and although Mr. Clover finds convincing the claim that in co-residential colleges ``emotional tensions will be reduced by the possibility of easy non-sexual friendships between men and women''1 I find it difficult to believe that the even tenor of college life would continue the same if colleges became mixed Halls of Residence. What gives college life its texture and value for undergraduates is that it is constituted of a number of overlapping circles of extended friendships. But whereas my friend's friend is eo ipso likely to be my own friend, my girl- friend's boy-friend, equally eo ipso, is not. There need be no rivalries in a segregated college. It excites no comment who sits with whom in Hall, and an undergraduate can sit with different friends without its being supposed that he either is disloyal or has been rejected. The first result of a college's going co-residential especially if the proportion of the sexes were unequal, would be to stimulate sexual competition. It would be a matter of pride not to be seen without an escort, and males would compete for the favours of the most-sought-after females. Already a good many undergraduates are disturbed by the sexual competitiveness of university life, but at least in college they do not have to enter that competition, and do not have to regard every meal in Hall, every tea in the JCR as a potential ``date'', and when things go wrong, they can withdraw into college and avoid agonizing encounters with the beloved. My enlightened friends are very brave about the trials of the lovelorn, and say it would be good for them to learn not to take their sorrows too seriously. But I do not believe that undergraduate love-affairs are always shallow, or that they ought to develop tough india-rubber hearts incapable of caring deeply enough to be hurt. Nor do undergraduates, and a later result of co-residence, if American experience is anything to go by, and especially if numbers became equal, would be to replace dates by ``steadies''. Continual competition is too rough on the emotions except for the outstandingly successful, and soon it becomes bad form to take someone else's partner. Except for a brief Paul Jones in the first term, a college would consist, at least as far as social relations were concerned, of couples. We should have lowered, in effect, the age of marriage by three or four years. And that would be a pity. Those who have settled down are disinclined to reach for the stars; and although for most people completeness of life is to be found in marriage, marriage is not the whole of life nor are personal relations between the sexes the only ones that we should value. Single-sex colleges foster friendships which, just because the friends are of the same sex, are not sexual friendships at all; they are for this very reason valuable, and provide the setting in which the young are encouraged to develop their minds and explore new ideas., they may be less intense than love-affairs, but are often longer lasting usually more conducive to the give-and- take of argument, and, because less committing, generally less likely to inhibit undergraduates from aspiration or experiment. If we make men and women inhabit the same quadrangles and staircases, we are bound to alter the character of college life. Many couples may enjoy the cosy domesticity of middle age in their early twenties, but they will have missed something which colleges have hitherto been able to give, and which constitutes the real reason for their existence.