The theme for this year's Tropentag, "Agricultural development within the rural-urban continuum" has a very special significance. The question of how agricultural production will respond to the dramatic shift in the rural-urban continuum is not only highly relevant but also vital for the future. In developing countries, rural areas still have the highest birth rates. Therefore, even with a high rural exodus, the absolute population in these areas will experience an increase lasting far into the next decade. The size of the rural population will not start to fall until later in this century. On the other hand, cities are growing at an unprecedented rate. From the estimated global population of 9.6 billion in 2050, 70% will be urban inhabitants. Already today the demand for food from a growing urban population in the developing countries is huge. A large middle-class is forming in the cities of these countries too, with a growing appetite for better quality, high protein foods. Must this increased overall demand be primarily met by buying on world markets? Or could local agriculture provide sufficient goods to cover the growing demand? Increased urbanization offers huge opportunities for development, not only for cities but also for rural areas and for agriculture. Urbanisation gives many small farmers the opportunity to make the leap from subsistence farming to producing for urban markets. This opportunity to earn an income can, for many families in rural areas, be the decisive step away from poverty and hunger. At the same time, new forms of "urban agriculture" are also offering interesting opportunities for development in the growing cities.