  The discovery of neutrino oscillations has shown that neutrinos, in
contradiction to a prediction of the minimal standard model, have mass.
Oscillations do not yield a value for the mass, but do set a lower limit of
0.02 eV on the average of the 3 known eigenmasses. Moreover, they make it
possible to determine or limit all 3 masses from measurements of
electron-flavor neutrinos in beta decay. The present upper limit from such
measurements is 2 eV. We review the status of laboratory work toward closing
the remaining window between 2 and 0.02 eV, and measuring the mass.
