The properties of the Earth’s coupled magnetosphere-ionosphere system are dominated by its interaction with the solar wind plasma, mediated by magnetic reconnection processes at the magnetopause interface. In this paper we focus on recent progress and remaining questions concerning the nature of these interactions, how they depend on the orientation of the interplanetary magnetic field (IMF), and the consequences which follow for internal dynamics. The progress we report, on flux transfer events and substorms during intervals of southward IMF, and magnetopause and tail processes during intervals of northward IMF, emphasise the great diagnostic power of combined in situ and remote sensing observations from space and on the ground.