Total helium production measurements in mixed-spectrum reactors are being used to test the helium production cross-section evaluations used for fusion reactor materials calculations, and to provide dosimetry input for reactor neutron spectrum characterization. Direct comparisons between helium measurements and helium predictions based on crosssection evaluations plus spectral adjustment procedures have pointed out discrepancies in ENDF/B-V cross sections, and have uncovered multiple-step reaction processes that produce enhanced helium in copper and iron at high neutron fluences. Significant variations have been observed in the ratios of helium generation measurements to predictions from reactor to reactor and from experiment to experiment in a given reactor. Based on these observed variations, the helium measurements are now being used as dosimetry input to examine differences in the calculated reactor neutron spectra using spectral adjustment procedures.