  Phenomenological Lagrangians and dimensional power counting are used to
assess isospin violation in the nucleon-nucleon force. The $\pi NN$ coupling
constants (including the Goldberger-Treiman discrepancy), charge-symmetry
breaking, and meson-mixing models are examined. A one-loop analysis of the
isospin-violating $\pi NN$ coupling constants is performed using chiral
perturbation theory. Meson-mixing models and the $^3$He - $^3$H mass difference
are also discussed in the context of naturalness.
