Dear Colleagues, it is our great pleasure to announce a Special Lecture at CT 2015 by Bill Lawvere entitled: "Alexander Grothendieck and the modern conception of Space". It was pointed out to us by Bill that we are celebrating this year the 50th anniversary of international category theory meetings (starting with 1965 La Jolla Conference on Categorical Algebra, organized by Helmuth Roehrl). This fact has been duly noted on the conference web site, see http://ct2015.web.ua.pt/ Hoping to be able to welcome you at CT2015, Walter Tholen and Dirk Hofmann PS: We would also like to remind you that the deadline for early registration is May 1. [For admin and other information see: http://www.mta.ca/~cat-dist/ ]