We study the process of farmer decision making, particularly the choice of productivity enhancing hybrid seed, of smallholder maize farmers in southern Mexico. Few studies regarding small-scale farming in developing countries have factored in social psychology together with economic dimensions in that context. While acknowledging the importance of risk preferences, there is still a lack of consensus on how these preferences influence the process of technology choice. We combine subjective beliefs derived from the Theory of Planned Behavior, with experimentally elicited risk and ambiguity preferences to predict the degree of farmers hybrid maize adoption in the coming season. Our results suggest that the higher farmers score on factors describing attitudes and subjective norms towards the use of hybrid seed, the higher is the degree of adoption. Farmers who are very risk averse score higher on attitudes towards the outcomes related to using hybrid seed, but intend to cultivate a smaller share of land with it. Ambiguity aversion is not significantly related to attitudes towards or the intended degree of adoption. Acknowledgement : This research was financially supported by the German Research Foundation (DFG).