One of the most spectacular predictions of Einstein's theory of general relativity is the occurrence of gravitational lenses in our galactic system.Nowadays the mastering of the mathematics together with the technology available to astronomers allow Einstein's prediction to be confirmed. Several reviews here give the reader the chance to under- stand the basic theoretical concept of gravitational lensing and to obtain an overview of observational work. The present state of the field and latest results are given in a large number of specialized papers. Anextensive source and subject index make these proceedings valuable also as areference book for all researchers active in the field.