  We study lattice QCD with staggered sea and Ginsparg-Wilson valence quarks.
The Symanzik effective action for this mixed lattice theory, including the
lattice spacing contributions of O(a^2), is derived. Using this effective
theory we construct the leading order chiral Lagrangian. The masses and decay
constants of pseudoscalars containing two Ginsparg-Wilson valence quarks are
computed at one loop order.
