  The various dynamical scales below the pion mass involved in $\pi^{+}$
$\pi^{-}$ atoms are sequentially integrated out using non-relativistic
effective field theory techniques. This allows us to systematically organise
the corrections to the energy levels and decay width. We present our results in
terms of a single unknown constant which may be obtained by matching to the
Chiral Lagrangian with electromagnetic interactions at two loops.
