The chemical evolution of the Milky Way will be discussed: in
particular, recent and accurate stellar  and nebular abundance data will
be compared with detailed chemical evolution models to infer important
constraints on nucleosynthesis and mechanisms of galaxy formation. We
will discuss the abundances of heavy elements such as C, N, O, 
alpha-elements, Fe, Fe-peak elements as well as  s- and r- process
elements.From abundance ratios in the solar vicinity we can infer the
timescales for the formation of the inner halo (no longer than 2 Gyr)
and the local disk (6-8 Gyr), while from abundance gradients we can
infer that the disk formed inside-out. We will show some new data and
models also for the Galactic bulge and conclude that the Bulge formed
very quickly (0.1-0.5 Gyr) during a strong starburst. Finally, we will
present models for the chemical evolution of the dwarf spheroidals 
(dSphs) of the Local Group, showing how their   [X/Fe] versus [Fe/H]
relations are different from those of the Milky Way. In particular, we
will show that  the abundances in the dSphs require a slow star
formation rate coupled with very efficient gas removal (winds), leading
to the conclusion that these dwarfs are not likely to be the building
blocks of our Galaxy.