The present book has its source in the authors? wish to create a bridge between mathematics and the technical disciplines that need a good knowledge of a strong mathematical tool. The authors tried to reflect a common experience of the University of Bucharest, Faculty of Mathematics and of the Technical University of Civil Engineering of Bucharest. The necessity of such an interdisciplinary work drove the authors to publish a first book with this aim (?Ecua ?ii diferen ?iale cu aplica ?ii în mecanica construc ?iilor? ? Ordinary differential equations with applications to the mechanics of constructions, Editura Tehnic?, Bucharest, Romania). The present book is a new edition of the volume published in 1999. Unfortunately, the first author (M.V. Soare) passed away shortly before the publication of the Romanian edition, so that the present work is only due to the other two authors. It contains many improvements concerning the theoretical (mathematical) information, as well as new topics, using enlarged and updated references. We considered only ordinary differential equations and their solutions in an analytical frame, leaving aside their numerical approach. Compared to the Romanian edition, this volume presents the applications in a new way.