A meeting was held from the 24th to the 27th of August 2015 in Montpellier, France, on Frankia-actinorhizal plants relations. This meeting was the 18th of the series that began in 1978 at Harvard Forest, USA. The initial meeting was sparked by the first isolation of a microbe from a Comptonia peregrina root nodule in pure culture, which had morphological features similar to those of the Frankia symbiont in nodules and was capable of forming nodules on its host (Callaham et al. 1978). This effectively boosted research on the symbiosis. The 2015 meeting was the opportunity to have 80 scientists from 17 different countries, present 34 oral presentations and 51 posters. The object was to exchange ideas on a range of subjects, initiate projects and discuss various controversies. The Montpellier meeting was opened by Jean-Marc Chataîgner, the IRD deputy managing director who outlined the opportunities and challenges facing scientists working on actinorhizal plants. Then there was an invited presentation by Allan Downie, Emeritus fellow at the John Innes Centre, Norwich, UK, who outlined the positive and negative aspects of the actinorhizal symbiosis research in comparison with the Legumes-rhizobia symbiosis.