In the current paradigm of star formation magnetic fields playa very central role. Indeed, they probably help or even channel theinitial gravitational collapse of the parent molecular cloud. Buttheir most spectacular effect is certainly the production ofubiquitous, powerful, bipolar self-collimated jets. Also, in the lastdecade, evidence has come that in such systems a magnetosphere linksthe protostar to its surrounding accretion disc. I will first briefly review the magnetohydrodynamic models of jets from youngstars. Then, I will discuss some constraints on the magnetosphericinteraction since accretion must proceed despite strong stellar magneticfields. Finally, I will introduce the 3Reconnection "X-wind" scenariothat leads to episodic jet formation with efficient removal ofprotostellar angular momentum.