REDF, formerly known as the Roberts Enterprise Development Fund, based in San Francisco (USA) has produced this paper from over 10 years of REDF's experiences mixing business practices with social mission. This paper considers some central issues when considering whether to choose a not-for-profit or a for-profit structure. Our thanks and acknowledgements go to REDF for sharing this report with us - please take a look at www.redf.org for more information about their work. Also see REDF's report "Social Impact Report 2005: What A Difference A Job Makes - The Long Term Impact of Social Enterprise Employment."