Workshop participants will discuss recent progress and plans to determine the hadronic light-by-light scattering contribution to the muon anomalous magnetic moment, which is expected to contribute the largest uncertainty in the Standard Model prediction. The goal of the workshop is to estimate current and expected systematic errors from lattice QCD, dispersive methods, and models  and create a plan to address them in time for new experiments at Fermilab and J-PARC. For more information, please visit the workshop web site.