This chapter defines 'farmer' broadly as someone engaged in agriculture on a full or part-time basis, including laborers as well as those working in a management capacity either on their own land or someone else's property. One of the most persistent ideas about Roman farmers is that they were largely self-sufficient and so had a limited impact on the broader Roman economy. It is hardly surprising that the concept of self-sufficiency, comes up so frequently in modern discussions of Roman farming. The chapter leaves the issue of necessary purchases to one side for the moment and focuses on the idea of self-sufficiency in modern scholarship about Roman farmers. Sometimes self-sufficiency is part of a strategy that involves specialized production for the market. Some conceive of self-sufficiency as an ideal rather than an economic practice that farmers could actually achieve. The chapter also presents an overview of this book.