Lyman α (Lyα) is the intrinsically most powerful spectral probe of ongoing star formation, and the only one easily accessible at redshifts z > 2.5. For low mass galactic building blocks which have low luminosities from hot dust, Lyα is currently the only probe available. However, its large absorption cross section in neutral hydrogen leads to strong radiative transfer effects and the interpretation of the line strength is far from straightforward. I will present results from two studies aimed at improving our understanding of Lyα emission from galaxies: a Hubble Space Telescope (HST) imaging project of spatially resolved Lyα, Hα and continuum in a small number of galaxies in the local universe, and a combined study of Lyα and Hα from an identical cosmic volume at z = 2.2.1 will also outline LARS a new major Lyα imaging study of galaxies in the local universe that will be carried out with HST in cycle 18. Studies at high spatial resolution of nearby starburst galaxies reveal the presence of very massive star clusters where a significant fraction of the star formation takes place. In the context of dwarf galaxies, we have studied a sample of four luminous blue compact galaxies with the HST and found that they seem to be the most efficient cluster formers of all galactic systems. We also note the presence of a near infrared flux excess that seems to ubiquitous in young clusters.
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