This paper, a contribution to the New Climate Economy project, compares the opportunities or economically attractive low-carbon investment opportunities in five cities. Five recently completed studies examined the economic case for investment in low-carbon development in Leeds in the UK, Kolkata in India, Lima in Peru, Johor Bahru in Malaysia and Palembang in Indonesia. This paper compares the results of these studies and demonstrates that there is a compelling economic case for cities in both developed and developing country contexts to invest, at scale, in cost-effective forms of low-carbon development.