Hello. Let me give you my suggestions. I'm still newbie to this fascinating area, but here goes the books I've been reading, by order of preference: - Michael Barr and Charles Wells, "Category Theory for Computing Science", Prentice-Hall; - Michael Arbib and Ernest Manes, "Arrows, Structores, and Functors", Academic Press; - Saunders Mac Lane, "Categories for the Working Mathematician", Springer-Verlag; - David Pitt et al, "Category Theory and Computer Programming", Springer-Verlag. This last item is the proceedings of tutorial and workshop, containing both very introductory and accessible papers, and research work. Possibly the choice of these books reveals some bias I have towards computer science. Cheers, -- *** Rodrigo Martins de Matos Ventura <yoda@isr.ist.utl.pt> *** Web page: http://www.isr.ist.utl.pt/~yoda *** Teaching Assistant and PhD Student at ISR: *** Instituto de Sistemas e Robotica, Polo de Lisboa *** Instituto Superior Tecnico, Lisboa, PORTUGAL *** PGP fingerprint = 0119 AD13 9EEE 264A 3F10 31D3 89B3 C6C4 60C6 4585