Report responding to a request made at the CGIAR meeting in May 1988 that TAC examine a possible expansion of the CGIAR to include ten so called non associated centers. The report was first circulated in September 1990, and this is the final version. Appended to the document is an extract from the summary report of the CGIAR meeting of October-November 1990 where the document was discussed and actions taken on its recommendations.Reflecting, as it does, more than two years of work, the report is extensive. After reviewing the background, and describing the processes used, TAC proposes a revised statement of mission and goals for the CGIAR, and discusses long and medium term visions for the Group. Under the heading of natural resources management it appraises ICRAF and the IUFRO special program, IBSRAM, IFDC and IIMI. ICIPE is considered under the rubric of crop protection, and separate attention is given to bananas and plantains (INIBAP), vegetables (AVRDC), fisheries (ICLARM), and coconut. Under livestock diseases TAC considers ICIPE again, CRTA and ITC. The paper concludes with a discussion of the implications of the TAC recommendations for the CGIAR structure and resource needs.Work on the report began at TAC 49. The completed document was approved at TAC 52, discussed at TAC 53 and presented to the Group at the CGIAR International Centers Week, October-November, 1990. Some of the consequences of decisions taken were considered at the CGIAR meeting in May 1991