  The fundamental description of both structural properties and reactions of
light nuclei in terms of constituent protons and neutrons interacting through
nucleon-nucleon and three-nucleon forces is a long-sought goal of nuclear
theory. I will briefly present a promising technique, built upon the {\em ab
initio} no-core shell model, which emerged recently as a candidate to reach
such a goal: the no-core shell model/resonating-group method. This approach,
capable of describing simultaneously both bound and scattering states in light
nuclei, complements a microscopic cluster technique with the use of two-nucleon
realistic interactions, and a microscopic and consistent description of the
nucleon clusters. I will discuss applications to light nuclei binary scattering
processes and fusion reactions that power stars and Earth based fusion
facilities, such as the deuterium-$^3$He fusion, and outline the progress
toward the inclusion of the three-nucleon force into the formalism and the
treatment of three-body clusters.
