The main objective of this paper is to evaluate and analyse technical efficiency (TE) levels for hillside farmers under different levels of adoption of soil conservation in El Salvador and Honduras. A switching regression model is implemented to examine potential selectivity bias for high and low level adopters, and separate stochastic production frontiers, corrected for selectivity bias, are estimated for each group. The main results indicate that households with above-average adoption show statistically higher average TE than those with lower adoption. Households with higher adoption have smaller farms and display the highest partial output elasticity for land. Constraints in the land and credit markets are likely explanations for these differences. In addition, all estimated models show that TE has a positive and significant association with education and extension.