  In the current paradigm of star formation magnetic fields play a very central
role. Indeed, they probably help or even channel the initial gravitational
collapse of the parent molecular cloud. But their most spectacular effect is
certainly the production of ubiquitous, powerful, bipolar self-collimated jets.
Also, in the last decade, evidence has come that in such systems a
magnetosphere links the protostar to its surrounding accretion disc.
  I will first briefly review the magnetohydrodynamic models of jets from young
stars. Then, I will discuss some constraints on the magnetospheric interaction
since accretion must proceed despite strong stellar magnetic fields. Finally, I
will introduce the "Reconnection X-wind" scenario that leads to episodic jet
formation with efficient removal of protostellar angular momentum.
