Book excerpt: This paper discusses the existing literature on migration and innovation, with special emphasis on empirical studies based on patent and inventor data. Other sources of micro-data are examined, too, for comparative purposes. A pilot database, based on patent filings at the European Patent Office is presented. It contains information on individual inventors, including their country of residence and of origin. Preliminary evidence suggests that immigrant inventors contribute to innovation not only in the United States, but also in selected European countries, where they often rank among the most productive individuals.