We study how aversion to risk and ambiguity aects the adoption of new tech- nologies by Ghanaian smallholder aquafarmers. We conduct a set of eld experiments designed to elicit farmers' risk and ambiguity preferences and combine it with survey- based information on their technology adoption decisions. We nd that aquafarmers who are more risk-averse were quicker to adopt the new technologies: a fast-growing breed of tilapia sh, extruded feed and oating cages. By contrast, ambiguity aversion has no eect on the adoption of the new tilapia breed and extruded feed. Furthermore, it slows down the adoption of oating cages - a technology which entails higher xed costs than the others - and the eect is diminishing in the number of other adopters in the village. We argue that these dierential eects are due to the fact that the technolo- gies are risk-reducing, with potential ambiguity about their payo distributions at the early stages of adoption. The ndings highlight the importance of distinguishing be- tween risk and ambiguity in investigating technology adoption decisions of small-holder farmers in developing countries.