Hadronic Interactions from Lattice QCD

I will present an overview of recent efforts to calculate the interactions among hadrons using lattice QCD. After outlining the techniques that are used to extract scattering parameters, I will present the latest calculations of meson-meson scattering, baryon-baryon scattering and multi-meson systems obtained with domain-wall valence quarks on the staggered MILC lattices by the NPLQCD collaboration. Estimates of the computational resources required to achieve precision results in the baryon sector will be discussed.