  We discuss questions related to renormalization group and to nonperturbative
aspects of non-Abelian gauge theories with N=2 and/or N=1 supersymmetry.
Results on perturbative and nonperturbative $\beta$ functions of these theories
are reviewed, and new mechanisms of confinement and dynamical symmetry breaking
recently found in a class of $SU(n_c)$, $USp(2n_c)$ and $SO(n_c)$ theories are
discussed.
