It has been recognized for more than a decade that in spiral galaxies and in the present epoch stars form in giant molecular clouds, which typically are distributed along the spiral arms of the galaxies. The question has been: "How do the stars form?" The Principal Investigator (PI) of this grant proposes to study this formation process both observationally and by numerical modelling. In particular, he proposes to investigate the Herbig-Haro objects in nearby molecular clouds, which are dense concentrations of gas and dust, within many of which stars seem to be assembled. Furthermore, the newly forming stars appear to be surrounded by accretion disks and they reveal themselves by bipolar ejections of matter perpendicular to the accretion disks. One of the PI's proposed projects is to investigate these bipolar flows.