New observations have been made of Faraday rotation in decameter-wavelength radio bursts from the planet Jupiter. Data obtained during six Io-B storms clearly indicate that an appreciable fraction (20→30%) of the observed Faraday rotation occurs in the Jovian magnetosophere. All of the Faraday rotation observed during a single Io-A storm can be accounted for by Earth's ionosphere. Measurements of the Faraday effect in Io-B emissions indicate that the source is in Jupiter's northern magnetic hemisphere. Observations of the Faraday effect in Io-C emissions are proposed to determine its location as well. ¿ American Geophysical Union 1989