Today, in the early 21st century, goods, information, services, financial capital and human beings are flowing across national borders at an everaccelerating rate. In this context, transnationalism has become a key paradigm in the study of international migration and urbanism. This theme issue on ''Immigrants and transnational experiences in world cities'' explores these new trends in contemporary international migration, with respect to transnational communities and geographies, in articles grouped according to four themes: international migration and world cities; highly-skilled and low-skilled immigrants; economic impacts; and immigrant experiences in world cities.