Traditions are dangerous; doubly so in science. Traditions are unchanging; science is about change. This was the 4th International Colloquium on Carbohydrate Metabolism in Pregnancy and the Newborn to be held in Aberdeen, and by now the form is set. How much its content has changed is a matter of nice judgement and not under the control of the organizers. It is not within their power to bring news of revolution, if there has been no revolution. Certainly many of the speakers had kent faces from previous Aberdeen meetings, but so they would be at any meeting on diabetes anywhere in the world. The written proceedings of scientific conferences have purposes other than to record changes: sometimes they need to state a consensus. The 3rd Colloquium came to an agreement about the importance of prepregnancy recognition and control of abnormalities of carbohydrate metabolism. The 4th set out to examine what results it had achieved. Much of this book is taken up with follow-up studies of the applications of similar regimes in different parts of the world. Since the first Aberdeen meeting in 1973, progress in the manage­ ment of diabetic pregnancy has been slow and steady, but the change in the city and the society where the meetings took place has been fast.