  The characteristics and properties of the stellar populations and
evolutionary histories of Local Group galaxies are summarized and compared to
predictions of cosmological models. No clear signature of the re-ionization
epoch is observed; in particular, there is no cessation of star formation
activity in low-mass dwarf galaxies at the end of re-ionization. Arguments
against the morphological transformation of dwarf irregular into dwarf
spheroidal galaxies are derived from their pronounced evolutionary differences
at early epochs as evidenced by the offset in the metallicity-luminosity
relation between gas-rich and gas-poor dwarfs. While there is increasing
evidence for past and ongoing accretion events the overall importance of dwarf
galaxies as building blocks remains unclear considering their differences in
modes of star formation and detailed chemistry.
