During the last decade or so vaccine development has been facilitated by rapid ad- vances in the molecular and cell biology ofthe immune system. This has laid the foundations of a new generation of vaccines exemplified by subunit vaccines produced through gene cloning and by synthetic peptides mimicking small regions ofproteins on the outer coat ofvi- ruses. However, as subunit and peptide vaccines are only weakly or non-immunogenic, there is areal need for strategies to improve their potency. This book contains the proceedings of the 5th NATO Advanced Studies Institute (ASI), "Vaccine Design: The Role of Cytokine Networks," held at Cape Sounion Beach, Greece, during 24 June-5 July 1996 and deals in depth with the role ofbasic immunology in the regulation of immunity and vaccine design. Special emphasis is given to the use of cyto- kines in conjuction with vaccines with the aim ofimproving their potency or the use ofvac- cines designed to improve cytokine production. We express our appreciation to Dr. J.-L. Virelizier and Dr. G. Kollias for their cooperation in planning the ASI and to Mrs. Concha Perring for her excellent production ofthe manuscripts. The ASI was held under the sponsor- ship of NATO Scientific Affairs Division and generously co-sponsored by SmithKline Beecham Pharmaceuticals (Philadelphia). Financial assistance was also provided by Connaught Laboratories Ltd. (Ontario), Pasteur Merieux (Marcy I 'Etoile), Biochine (Siena), Help SA (Athens), and Avanti Polar Lipids Inc. (Birmingham, USA).