The Neuronal Ceroid Lipofuscinoses is a lysosomal disease which have recently been confirmed by important genetic studies on the NCL which revealed a diversity of at least 8 gene loci related to this group of diseases. ECA- NCL represents a multi-national, multi-disciplinary network of researchers on the NCL which have provided new data on this group of diseases. In this book, clinical features, neuroradiological and electrophysiological data, morphological aspects, genetic data and biochemical results will be provided. This book is written for active researchers on NCL and other lysosomal and neurodegenerative diseases, as well as for those interested in NCL for other reasons, foremost patients (and their parents). Tables, illustrations, and most recent references will accompany the text produced and edited by an editorial board consisting of participants of this ECA- NCL . At the end of this presentation, future lines of research including therapies - will be outlined and emphasized what will have to be done to arrive at complete elucidation of this group of progressive neurodegenerative disorders.