The Federation of American Societies for Experimental Biology has sponsored a series of Summer Conferences since 1982 with great success. These have been held annually at Vermont Academy in Saxtons River, Vermont. In this application we are asking for support of a new conference on Folic Acid, Vitamin B12 and One-carbon Metabolism. A conference combining these three areas of research is long overdue. Each of these fields has grown rapidly in recent years with many exciting developments. Some of these are: the use of nitrous oxide to specifically inactivate B12 coenzymes to produce vitamin B12 deficiency in primates and humans, the recognition that polyglutamate forms of folate are the natural coenzyme forms and that the length of the polyglutamate chain influences the rate of the reaction, and the demonstration that rats spontaneously develop hepatomas when kept on a diet devoid of methyl groups. While some specialized meetings have been held devoted to the individual topics, we are aware of no recent single meeting which has attempted to bring together individuals working in these related fields. The format of the meeting will be similar to that used in the Gordon Research Conferences; the meeting will last 4 1/2 days with 9 major sessions consisting of four speakers each. Therefore, there will be 36 invited speakers. There will also be poster sessions reviewed in the evenings. Attendance at the conference will be limited to about 150 participants.