The aim of the topical workshop is to assess the state of the art of the theoretical determination of the muon anomalous magnetic moment, aμ , in view of the anticipated new measurement of the E989 Muon g-2 experiment in Fermilab, which is expected to improve the present precision by a factor of four, and the new approach to measure aμ under development by the E34 collaboration at J-PARC. The workshop will focus on aμHLO , the leading hadronic contribution to the muon g-2, both analyzing the most recent experimental and theoretical results for its determination, as well as taking into consideration the most recent dedicated lattice calculations. Particular attention will be devoted to MUonE, a recently proposed experiment at CERN which aims at measuring the running of the electromagnetic coupling constant in the spacelike region by scattering high-energy muons on atomic electrons of a low-Z target through the process μe → μe. The differential cross section of this process provides the direct measurement of aμHLO and, therefore, an independent determination of the theoretical prediction for aμ competitive with the timelike dispersive approach.