Advances in the genetic modification of agricultural seeds have allowed a range of new opportunities for manipulating seed traits according to production, market and environmental concerns. As seed varieties continue to become increasingly differentiated, preferences for specific seed traits may be expected to impart significant effects on farmer demand for new seeds. This paper proposes a model of technology adoption that integrates demand for traits of new technologies with the potential for heterogeneity based on farm and farmer characteristics. The model is applied to recent GM corn adoption data from Minnesota and Wisconsin farmers, and uses conditional logit and mixed multinomial logit econometric models to estimate the effects of traits and farm and farmer characteristics on adoption outcomes.