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).