Late-type dwarf galaxies (dwarf irregulars and blue compact dwarfs
(BCDs)) are extremely important to cosmological issues since, with
their high gas content and low metallicity, can be regarded as
analogues to primeval galaxies. 
Detailed star formation histories can be derived in these systems from
deep color-magnitude diagrams of their resolved stars. I will present
some results that we have recently obtained with HST for three very
interesting late-type dwarfs outside the Local Group: NGC 1705, IZw18
and NGC 4449.