Aluminum (Al) toxicity is an important growth‐limiting factor for plants in many acid soils. The problem is not always economically correctable with conventional liming practices. But plant species and genotypes within species differ widely in tolerance to excess Al, and some of these differences are genetically controlled. Hence, an alternative or supplemental approach to the problem is to select or breed plant genotypes having greater tolerance to Al. A plant genetic approach has great potential for solving difficult soil fertility problems such as Al toxicity in acid subsoils. An important part of this approach is the determination of plant genetic, physiological and biochemical mechanisms by which plants tolerate mineral stress. Better understanding of stress tolerance mechanisms could lead to the development of more tolerant plants and more effective liming and fertilization practices for plants already in use. The objective of this presentation is to discuss our state of knowledge concerning the range of plant tolerance to excess Al, genetic control of tolerance and release of Al‐tolerant germplasm, and plant physiological and biochemical characteristics associated with differential Al tolerances among genotypes within species.