This report on progress in the magnetosphere covers the calendar years 1967–1970 inclusive. Bibliographical coverage is also for the period 1967–1970: therefore, results presented at conferences but not yet available in published form may be cited.

The topic of the magnetosphere has been divided into five sections: magnetopause; magnetosphere structure, tail, and plasma sheet; convection and the plasmapause; storms and substorms; and ring current and energetic particles. These divisions have some overlap and are somewhat arbitrary, but they form a convenient framework for dividing up the new theory and observations. Substantial progress has been made in both theoretical and experimental work and in development of new technology. It is now possible to measure all the parameters (electric and magnetic fields and particles in all energy ranges) known or believed to be important in the physics of the magnetosphere.