  This talk reports the latest indications of an anomaly in the measurements of
atmospheric neutrinos. New results from Soudan-2 and Super-Kamiokande provide
evidence that the ratio of nu_mu to nu_e interactions is not as expected. High
energy Super-Kamiokande data indicates the cause is a deficit of upward-going
nu_mu, and the zenith angle dependence of the effect is consistent with
neutrino oscillations. Upward-going muon measurements by several detectors are
discussed, but in total they provide inconclusive evidence for the anomaly.
