The biome Pampa, in Brazil, is under threat from expansion of agriculture and overgrazing. Although several sustainable livestock farming innovations are currently available to farmers in the region, adoption rate remains low. This paper uses the theory of planned behavior (TPB) to identify the psychological factors that influence farmers' intention to adopt improved natural grassland, an innovation that increases productivity at farm level and reduces damage to the environment. The TPB hypothesizes that adoption is driven by intention, which in turn is determined by three psychological constructs: attitude, subjective norm, and perceived behavioral control. Results show that the intention of farmers to use improved natural grassland was mainly determined by their perceptions about the social pressure to use this innovation (subjective norm), followed by their perceptions about their own capability (perceived behavioral control) to use this innovation, and their evaluation of the use of improved natural grassland (attitude).