Testing m(up)=0 on the Lattice

A massless up quark is an intriguing solution to the strong CP problem. We discuss how lattice computations can be used in conjunction with chiral perturbation theory to address the consistency of $m_u=0$ with the observed hadron spectrum and interactions. It is not necessary to simulate very light quarks-three flavor partially quenched computations with comparable sea and valence quark masses on the order of the strange quark mass could suffice.