  Tools for calculating the Renormalization Group Equations for renormalizable
and non-renormalizable operators in various theories are reviewed, which are
essential for comparing experimental results with predictions from models
beyond the Standard Model. Numerical examples for the running of the lepton
mixing angles in models with non-degenerate see-saw scales are shown, in which
the best-fit values of the experimentally favored LMA solution are produced
from maximal or from vanishing solar neutrino mixing at the GUT scale.
