Lithium production from several stellar sources (C-stars, massive AGB stars, Type II supernovae and novae) as well as from galactic cosmic rays (GCR) is included in a succesfull model for the chemical evolution of the Milky Way in order to predict the evolution of the 7Li abundance (A(Li) = log(7Li/H) + 12) as a function of [Fe/H]. From comparison with the oservational data we infer the following conclusions: 1) Li production from novae seems to be necessary to explain the steep rise of the Li abundance for metallicities larger than [Fe/H] = — 1.0 dex, 2) Li production from SNe II should be less than assumed before in order to reproduce the long plateau observed for A(Li) for low metallicities, 3) Li production from C-stars is negligible relative to Li production from massive AGB stars which is instead a necessary Li- source, 4) Li production from GCR should contribute by no more than 20% to the solar Li abundance.

We present the Light Element Evolution resulting from our new Chemical Evolution model. The LiBeB evolution is correctly fitted by taking into account several sources: Big Bang, Galactic Cosmic Ray Nucleosynthesis, the ν-process, novae and AGB and C-stars.

Results of evolution of light elements (6LiBeB) based on supernova (SN)-induced chemical evolution model are presented. We point out an important property of light elements as a cosmic clock in metal-poor stars.

We analyze the evolution of 7Li/H using the basic model for the galactic chemical evolution (GCE) described by Brown (1992) and a numerical procedure which allows to estimate the contribution of the red giants to the enrichment of lithium in the interstellar medium (ISM).

Some conclusions are drawn from the Conference as to Big Bang Nucleosynthesis, cosmic rays, AGB star evolution and various kinds of mixing processes in stars.

The symposium has shown that our subject is well and very alive. It is progressing rapidly, thanks to a large amount of new observational data, obtained in particular by a young generation of competent astronomers. It is encouraging, incidentally, to note the large fraction of women in this generation. When I started in this field, some forty years ago, the feminine contribution was much smaller. I plan to review the state of the situation for each of the three nucleosynthesis processes responsible for the light elements: Big Bang Nucleosynthesis (BBN), galactic cosmic ray spallation of interstellar nuclei (GCR) and stellar nucleosynthesis. I will point out their successes, their riddles and possible avenues by which these riddles could be solved. I plan first to review the observations.