Among the several distinct ways of formulating and quantizing a Hamiltonian system, the light cone approach enjoys special status because it has the largest stability group. The aim of this volume is to present recent achievements and open problems in this rather unusual quantization framework to a large audience. The formulation is set up in a comprehensive introduction where the issues are also clearly indicated with specific examples: vacuum structure, signature of non-perturbative effects, chiral symmetry breaking, light cone gauge theories, etc. The following chapters address these topics through a selection of the most relevant contributions presented at Les Houches. This volume should prove valuable to newcomers in the field, and graduates and academics.