On the theoretical uncertainties in the muon anomalous magnetic moment

I present a fairly detailed discussion of various contributions to the anomalous magnetic moment of the muon a_mu. I try to give an unbiased evaluation of the validity of the SM prediction for this quantity and to point out some delicate issues involved in its calculation. I conclude that the theory uncertainties in the SM prediction for the muon anomalous magnetic moment are underestimated and a great deal of work will be required to reduce these uncertainties to the level required by experiment.