Synopsis Continuous deforestation for fuel has resulted in soils that are deficient in nitrogen. Mineral fertilizer application are more attractive to foresters but it involves heavy repeated application as the recovery is very low. Such heavy application is not only expensive but also causes negative effects on ground water through an increase in their nitrate content leading to eutorophyzation of water ecosystems. Increased reliance on N-fixing trees could be an important contribution to soil fertility and national economics in the future. It is in this context within which the interest for Frankia-plant symbiosis stands. Frankia induce N-fixing root nodules actinorhiza, on more than 280 species of woody plants and is known to have considerable N-fixation even at young age. This book provides comprehensive information on this important biofertilizer, having immense potential in improving forest productivity.