The main objective of this research is to compare estimates of technical efficiency obtained from the stochastic frontier approach for two samples of farmers of private and water user associations in the Nefzaoua Oases region (Tunisia), which are characterized by a severe scarcity of water and especially a high degree of salinity. Technical inefficiency effects are modeled as a function of farm-specific socioeconomic factors. Results suggest that both systems are technically inefficient. On average, the private system is found to be slightly more efficient than the associative one. Date yield could be explained mainly by four variables: water quantity applied per palm tree, labor per palm tree, phosphate per palm tree, and water salinity. Output elasticities of all inputs are found to be positive and significant except for the farmyard manure. Water salinity has a considerable negative impact on date productivity. For the technical inefficiency model, none of the socioeconomic variables seem to matter.