  We review the Lyan alpha emission in local star-forming galaxies. In most
cases as already shown by the IUE, the emission is absent or much weaker than
expected. This occurs because Lyman alpha photons can be resonantly scattered
by the neutral gas and destroyed by even very low amounts of dust. However new
Hubble Space Telescope observations (HST) indicate that other factors such as
the velocity structure of the gas play a crucial role. Gas flows are likely to
occur as powered by the kinetic energy released via stellar winds and
supernova. We propose a scenario based on the hydrodynamics of superbubbles
powered by massive bursts of star formation that naturally accounts for the
variety of Lyman alpha line detections in star-forming galaxies. We caution
with the attempts to derive the co-moving star formation rate at high redshift
from Lyman alpha emission searches.
