  I discuss isospin violation in an effective field theory appraoch of the
nucleon-nucleon interaction. The observed leading order charge independence
breaking is explained in terms of one-pion exchange together with a
four-nucleon contact term. A general classification scheme of corrections to
this leading order results is presented and an explanation is offered why
charge-dependent pion-nucleon coupling constants can not play a role in the
observed isospin violation in the NN scattering lengths. Charge symmetry
breaking, the size of $\pi\gamma$-exchange graphs and the pionless theory are
also discussed.
