What determines galactic evolution?
  We are briefly introducing the most important ingredients to study galactic evolution. In particular the roles of star formation, nucleosynthesis and gas flows. Then we are discussing the two different approaches to galactic evolution: the stellar population approach (chemical evolution models) and the hierarchical clustering scenario for galaxy formation. It is shown that there are still some controversial points in the two approaches, as evident in the brief summary of the discussion. 
Francesca Matteucci (Department of Astronomy, University of Trieste)