These two issues – the environmental effectiveness of organic regulations and the environmental efficiency of organic agriculture at farm level – provide the focus of this paper. We adopt the approach to firm-level environmental performance evaluation used in the literature on productive efficiency analysis (Dyckhoff and Allen, 2001; Färe et al., 1989; Hailu and Veeman, 2001). This entails comparison of organic and conventional farm performance using multiple environmental indicators3 to measure differences in output per unit of environmental impact and input (environmental efficiency) and differences in environmental impact per unit input (environmental effectiveness).