Technical Abstract: Quantitative disease resistance, conditioned by many loci of relatively small effect, is important in ecological and agricultural systems. The importance of quantitative resistance in agricultural systems has lead to much applied research in this area and the accumulation of a building body of knowledge related to its genetic architecture, but the incomplete and inconsistent nature of the phenotype has slowed the uncovering of its mechanistic basis. Basic research efforts, on the other hand, have focused more on qualitative resistance, conditioned by major single genes or R-genes, because it is both important and relatively tractable. Quantitative resistance mechanisms have been more difficult to uncover, but a framework to characterize these mechanisms is emerging through the convergence of applied and basic research. The application of careful phenotypic analysis and development of a new generation of powerful quantitative genetics tools will lead to more effective utilization of natural resistance alleles and deeper understanding of plant defense. As we approach this convergence, it appears that a diversity of mechanisms will be shown to be implicated in quantitative resistance.