Rice, with its rapidly growing importance as a staple food, plays a key role in West African diets, accounting for nearly 40% of the total volume of cereals consumed. In the context of the 2008 food price crisis, several West African countries have proclaimed their goal of rice self-sufficiency by 2050, through expansion of cultivation areas and intensification of rice farming. The objective of this thesis is to assess the production and market risks associated with increased rice production in West Africa and to evaluate their impact on the welfare and food security of rice producers.In a first study, the potential impact of reallocating resources such as land, labor or capital to rice production at the expense of other staple food crops such as cassava, maize, millet, sorghum or yam is examined. On average across the region, rice yields are more variable, by about 20%, than those of the other five staple food crops. Rice tends to have more variable yields than the other crops in areas where they are traditionally grown (i.e., tubers in the Guinean zone, and sorghum and millet in the Sahelian and Sudanian zones). Rice yields, across all cropping systems, tend to be more variable than those of other crops in areas where rainfall variability is greatest.The impact of agricultural practices and climate risk on rice yields is examined in a second study, via the construction of rice production functions for four representative cropping systems (i.e., rainfed lowland system, improved lowland system, irrigated system, rainfed upland system). The statistical study of yields shows that intensive practices (i.e., use of fertilizers, pesticides, improved varieties, improved water management) significantly increase average yields but do not lead to a stabilization of yields, at the scale of an administrative region 1. In the Guinean and Sudanian zones, where water scarcity and drought risks are lower, it is the frequency of weeding that has the greatest impact on average yields. In contrast, in the Sahelian zone, the spatio-temporal variability of rainfall explains about 50% of the variance of yields, for non-irrigated systems.Finally, the impact of agricultural risks and constraints, and the effect of changes in the economic context, on the decision making of rice farmers is assessed using a microeconomic model. The results of this analysis show that the economic situation of households influences their choice of investment in rice farming. Farmers locked into the poverty trap are, by definition, constrained by the lack of available capital at the beginning of the cycle, and thus have no opportunity to invest in inputs, unlike households that have been able to generate a surplus and save part of their income. This poverty trap is strongly correlated with the climatic context, since in regions where water is scarce and the risk of drought is high (i.e., the Sahelian and North-Sudanian zones), yields are low and water is the limiting factor, so that the addition of fertilizer does not generate significant income.Improving rice production is, in the current context, strongly constrained by the risks and constraints faced by rice-producing households. Our results show that rice self-sufficiency may not be effective in achieving food security in West Africa, as production can vary considerably depending on climatic conditions.