Throughout the developed and developing world, millions of people engage in urban and peri-urban agriculture (UPA) for a variety of reasons and using different production and distribution systems. In differentiating ‘urban’ from ‘rural’ production systems, perhaps it is helpful to ask the question ‘what is agriculture’? According to the Oxford Dictionary, ‘agriculture’ is the science or practice of farming, including cultivation of the soil, for the growing of crops and the rearing of animals to provide food, wool and other products. Agriculture taking place in urban settings will have characteristics that distinguish it from rural types of cultivation. Although both types of production systems share certain biophysical and natural determinants, an urban classification includes additional attributes, such as unique productivity constraints (issues of legality, land tenure, pollutants), spatial form (vacant lots, rooftops) and practical function (husbandry, crops, informal source of income and employment).