From 23 to 27 October 1989, the Study Week Science for development in a solidarity framework was held at the seat of the Pontifical Academy of Sciences in the Vatican. At the end of the Study Week the Holy Father John Paul II addressed an allocution to the participants during a special audience; the allocution, which gave a particular relevance to the Study Week, is published in this volume. Those who attended the Study Week have sent a warm and deferential message of gratitude to the Holy Father, stating that the ideal setting provided by the Pontifical Academy of Sciences had enabled them to discuss problems of great seriousness in a quiet atmosphere of intellectual freedom. They expressed the hope that their efforts would contribute, however modestly, to the progress of science and to an improvement of the human condition. Along these lines the Study Week also had the attention of S.E. Cardinal Roger Etchegaray and of Archbishop Pietro Rossano, whose speeches given at the Study Week are published here. The Study Week was organized under my direct supervision by Professor Alberto Quadrio Curzio and by Rev. lng. Renato Dardozzi, with the special help of Msgr. Martin and with relevant contribution by Fr. Gianpaolo Salvini S.J. On the Study Week we have already analitically reported in a booklet called Science for development in a solidarity framework, edited by myself and Alberto Quadrio Curzio for the Pontifical Academy of Sciences in 1990. This volume, instead, is the final outcome of the Study Week and presents a very different structure as compared to the booklet. This is due to the results of the discussion during the Week and to the scientific evaluation of the editor of the volume, Alberto Quadrio Curzio, who has privileged the economic aspects of the Week itself, leaving aside some contributions we reported on in the 1990 booklet.