The exact title of the JD 11 was: “stellar and interstellar lithium and primordial nucleosynthesis”. The large amount of work recently done about lithium provided an incentive for a discussion among the members of several commissions of the IAU. Lithium is a peculiar element. Since it is not produced in supernovae (at least such a production is not proven and would be quite different from the production of the other elements) its presence in old material is a legacy of the primordial nucleosynthesis. But lithium is a fragile element, and from a theoretical point of view, there are arguments tending to conclude that, in old stars, this legacy has been depleted. This difficult problem is areal challenge, an has been the motivation for many different works. The analysis of the lithium behavior in well known stars, of all kind of ages, metallicities, structures, peculiarities etc. is therefore extremely useful in order to understand the physicalprocesse at work for lithium depletion, and the reader will find here many up-to-date data. The analysis of lithium in interstellar material provides an essential information. Many works about lithium are in progress throughout the world on the different points of interest, so that the General Assembly of the IAU was an excellent occasion to have a review of the recent progresses made in different areas. A summary of (nearly) each communication made during the Joint Discussion 11 may be found hereafter. Longer summaries of the talks, and summaries of the posters will be published in a forthcoming volume of the Memorie of the Società Astronomica Italiana.