The 15th International Frankia and Actinorhizal Plant Meeting was held from October 19th to 23rd, 2008, in Bariloche, Argentina. Frankia is an actinomycete that nodulates roots of a group of angiospermous plants. Frankia fixes atmospheric nitrogen symbiotically with its specific host plants in 24 genera within eight families. This was the first of the biennial meetings to be held in South America and only the second, after New Zealand, to be held outside of North America and Europe. Thirty four scientists and students from nine different countries in South America, North America, Europe and Asia attended. The site of the meeting, Bariloche, is in the Patagonian region of the southern Andean Mountains, where a distinct group of actinorhizal plants and their Frankia symbionts occur. These plants are in the tribe Colletiae (family Rhamnaceae) and the meeting participants had the opportunity to explore their natural environs from steppe to humid forest in the Nahuel Huapi National Park near Bariloche and to hear reports of the most recent research on this actinorhizal group. Much research progress has been made on Frankia and on actinorhizal plants since the first meeting was held at Harvard Forest in Petersham, Massachusetts in 1978. At that meeting, hosted by Dr. John Torrey, an icon in the field of Frankia research, the common interests of a small group of researchers had evolved from developments in three areas. The first area of advancement was the effort, sponsored by the International Biological Program, to establish a worldwide accounting for actinorhizal plants, then known to be comprised of 15 genera in seven “diverse” families. These morphologically “diverse” groups are now known to cluster together with other plant taxa, including legumes, in the subclade rosidae, apparently a taxonomic unit with plants predisposed to diazotrophic symbioses. The second impetus came from the increased recognition by foresters and other natural resource managers that actinorhizal plants possessed nitrogen fixation capacities equal to those of legumes and that actinorhizal plants conferred the dual benefits of superior host-plant productivity on poor soils and enhancement of soil nitrogen fertility. The third development was the first successful isolation of a Frankia strain (CpI1 from Comptonia peregrina) in pure culture and reinfection of a host plant by this isolate. This feat opened the door to a detailed understanding of this nitrogen-fixing actinomycete, its symbiosis with angiospermous host plants, and its potential for genetic improvement through biotechnology. Since the first conference, and even the most recent one held at the University of Umea in Sweden in 2006, substantial changes in emphasis and developments have occurred and were featured at this 15th meeting in Argentina. These included (1) notable advancements in E. Chaia (*) Universidad Nacional del Comahue, Centro Regional Universitario Bariloche, Quintral 1250, Bariloche 8400, Argentina e-mail: echaia@crub.uncoma.edu.ar