This book is based on a set of lecture notes developed in teaching a course in the dynamics of structures during the past ten years. It presents a treatment of dynamics of structures equally applicable to civil engineering structures, aircraft structures, and space craft. Thereforce, in presenting the material, emphasis is placed on methods of analysis. There is no attempt to distinguish among various types of structures because it is believed that the basic principles and methods of analysis apply to frame and shell structures alike. In developing the subject matter, lumped and distributed parameters are treated in parallel.