Support for organic farming is a key strategy of rural development policies in several countries. This paper studied the spatial pattern of participation in agro-environmnetal policy the policies designing to foster diffusion of organic farming. The ultimate goal is to investigate the impact of local factors for improving the policy targeting. Indicators of spatial association and a spatial econometrics model were performed for the analysis. The results show regional agglomeration effects of the rate of participants to the measures adopted to promote organic farming. In addition, a spatial relation among the farms that obtain public support is found, highlighting that the diffusion of participation is driven mainly by imitation process and external economies of scale.