The 1979–82 quadrennium was a time of unprecedented excitement and achievement in Jovian magnetospheric physics, highlighted by the traversais by Voyager‐1 and ‐2 (V‐1, ‐2) in March and July 1979. Our knowledge has been expanded immensely by Voyager observations and their interpretations, and this review is devoted largely to them. Not to be overlooked, however, is activity in the areas of continuing Pioneer‐10 and ‐11 (P‐10, ‐11) data analysis and ground based observations, both of which complement the Voyager results spatially and temporally.This report focuses on Jovian fields and plasmas (and under plasmas we include charged particles of all energies). Not included is the considerable body of observations of waves in Jupiter's magnetosphere, which are involved in plasma dynamics but which are covered in the companion report “Plasma Waves in Planetary Magnetospheres” by R. Anderson.