This volume collects the papers presented at the "Specialists' Meeting on Nuclear Level Densities", held in Bologna 15 - 17 November, 1989, which gathered most of the scientists working in the field. The papers cover all the major aspects of the level density problem both from the theoretical and the experimental viewpoint, including the subject of partial level densities. In particular, moment method, collective vector method, interacting boson model, static path approximation and combinatorial approach are discussed. Effects of the residual interactions and nuclear structure are also addressed, giving a state-of-art reveiw of our present knowledge on nuclear level densities.