The increasing resource and ecological challenges in agriculture necessitate agricultural intensification and resource optimization. This study focuses on agroecological intensification using organic practices. It compares the production efficiency of the organic and non-organic smallholder kale production systems in Kenya. Using survey data collected from Kenya, the study estimated production (cost and revenue) efficiency of the kale production system by conducting data envelopment and stochastic frontier analysis and subjected the efficiency measures to propensity score matching analysis. The results show no significant difference in cost efficiency between organic and non-organic kale producers. However, revenue efficiency and income per unit production cost are lower among organic than non-organic kale producers. The results also show that the efficiency and productivity of the organic smallholder kale production system are limited by a lack of inputs (especially manure) but not labor. This implies that improving the efficiency of the smallholder organic kale production system requires more use of organic manure as well as research and training on organic pesticides. The finding concurs with literature that reports organic input problems and lower productivity in organic than non-organic production systems in developing countries and Kenya, especially in vegetables. It also shows that the organic production system is more labor-intensive than the non-organic system.