Johan Bijnens, Niclas Danielsson, Timo A. Lähde Partially Quenched and Three Flavour ChPT at Two Loops Invited talk at Final EURIDICE Meeting: Effective Theories of Colors and Flavors from EURODAPHNE to EURIDICE, Kazimierz, Poland, 24-27 Aug 2006 Abstract A summary of recent progress in Chiral Perturbation Theory (ChPT) at the two-loop level is given. A short introduction to ChPT is included, along with an explanation of the usefulness of developing ChPT for partially quenched QCD. Further, our recent work in partially quenched ChPT is reviewed, and a few comments are given on older work in mesonic ChPT at the two-loop level. In particular, we quote the present best values for the low-energy constants of the $\mathcal{O}(p^4)$ chiral Lagrangian. LU TP 07-03, hep-ph/0701267