Dear categorists, Some of you may be interested in a Workshop on Lie groupoids and Lie algebroids, which is to take place near Sheffield, October 25-27. It is organised in conjunction with a regional LMS meeting on the preceding Wednesday afternoon, with lectures by Breen and Cattaneo. Further information can be found on <http://www.kchmackenzie.staff.shef.ac.uk/october07/>. The conference facilities allow only a limited number of participants, so if you are interested in coming, please contact Kirill Mackenzie or me as soon as possible. Ieke Moerdijk.