It is my task to summarize for you what we have learned today about the helium problem. Before attempting this, let me first very briefly outline the problem as it appears to us in 1970. It amounts to the questions: What is the fractional abundance of helium in different regions in the universe, is it the same in all places, and how did it originate?

The simple answers to these questions which appealed to many and seemed to have a reasonable basis in fact a few years ago were:

The He/H ratio is of ~ 25-30% by mass; the ratio is the same everywhere, and the helium was most probably synthesized in the early stages of a primordial fireball in which the universe began. However, for some time it has been clear that the situation is more complicated than this, as I pointed out in an article published last year in Comm. Astrophys. Space Sci.