The effects of immigration on the Thai economy are considerable, as the number of immigrants has increased rapidly since the turn of the century. Immigrant workers now contribute to all economic sectors, and are important for the workforce in industrial sectors such as construction and manufacturing and in some service sectors including private household services. Immigration is associated with an improvement of labour market outcomes of the native-born population, and in particular appears to increase paid employment opportunities. Immigration is also likely to raise income per capita in Thailand, due to the relatively high share of the immigrant population which is employed and therefore contributes to economic output. Policies aiming to further diversify employment opportunities for immigrant workers could also be beneficial for the economic contribution of immigration. How Immigrants Contribute to Thailand’s Economy is the result of a project carried out by the OECD Development Centre and the International Labour Organization, with support from the European Union. The project aimed to analyse several economic impacts – on the labour market, economic growth and public finance – of immigration in ten partner countries: Argentina, Costa Rica, Côte d'Ivoire, the Dominican Republic, Ghana, Kyrgyzstan, Nepal, Rwanda, South Africa and Thailand. The empirical evidence stems from a combination of quantitative and qualitative analyses of secondary and in some cases primary data sources.