Urban agriculture (UA) has long been dismissed as a fringe activity that has no place in cities; however, its potential is beginning to be realized. In fact, UA is about food self reliance: it involves creating work and is a reaction to food insecurity, particularly for the poor. Contrary to what many believe, UA is found in every city, where it is sometimes hidden, sometimes obvious. If one looks carefully, few spaces in a major city are unused. Valuable vacant land rarely sits idle and is often taken over – either formally, or informally – and made productive. Urban agriculture is a long-established livelihood activity that occurs at all scales, from the small family-held market garden to the large agri-business located on the fringe of a city. It supplies food to the city and income to those who farm. Above all, UA is making an important contribution to food security for those who do not have easy access. In essence, UA is the true realization of the statement that ‘necessity is the mother of invention’.