This synthesis paper informs the development community about the effects of climate change on migration patterns within and out of developing countries, concentrating on the economic aspects of migration. Empirical evidence shows that people in developing countries respond to climatic change by migrating internally. Evidence on the relationship between climate change and international migration is limited. The effect of climate change on migration decisions depends crucially on socio-economic, political, and institutional conditions. These conditions affect vulnerability to climate change and hence how important climate change is in determining migration decisions. Migration has been an effective response to climate variability and change in the past and might be one in the future, but only under certain pre-conditions. Access to information on the economic and social costs of migration, on advantage and disadvantages of potential destination locations, and the absence of credit constraints and other barriers can help potential migrants to make decisions that will improve livelihoods. Policy intervention is also required to reduce potential negative impacts in both the sending and receiving region. Badly managed migration is associated with high economic, social and psychological costs.