Debates about the relationship between agricultural technology and the conservation of crop genetic diversity are often hampered by unclear vocabulary and imprecise data. Various interpretations of the terms “modern variety,” “local variety,” “hybrid,” and “green revolution” are first explored, and then evidence is examined regarding the effect of modern varieties on intra- and intercrop diversity, risk, input use, and farmer decision-making. The objective is to urge a more reasoned debate about the future of plant genetic resources.