The NATO Advanced Studies Institute series Targeting of Drugs was originated in 1981. It is now a major international forum, held every two years in Cape Sounion, Greece, in which the present and the future of this important area of research in drug delivery is discussed in great depth. Previous ASIs of the series dealt with drug carriers of natural and synthetic origin, their interaction with the biological milieu, ways by which the latter influences such interaction, strategies by which milieu interference curtailing the function of drug carriers is circumvented and, more recently, with the application of drug carriers for the delivery of peptides and proteins. The present book contains the of the 7th NATO ASI Targeting of Drugs: Advances in System Constructs, proceedings held in Cape Sounion during 24 June -5 July 1993. As the title implies, the book deals with a variety of approaches to carrier design or modification that contribute to optimal carrier function. to Mrs Concha Perring for her assistance with the We express our appreciation organization of the ASI. We thank Dr. G. Deliconstantinos who, as chairperson of the Local Committee, contributed to the success of the Institute. The ASI was held under the sponsorship of NATO Scientific Affairs Division and co-sponsored and generously financed by SmithKline Beecham Pharmaceuticals (King of Prussia). Financial assistance was also provided by Liposome Technology Inc. (Menlo Park), Vestar Inc. (San Dimas) and Zeneka (Macclesfield).