This paper presents five versions of an international bilateral migration stock database for 226 by
226 countries. The first four versions each consist of two matrices, the first containing migrants
defined by country of birth i.e. the foreign born population, the second, by nationality i.e. the foreign
population. Wherever possible, the information is collected from the latest round of censuses
(generally 2000/01), though older data are included where this information was unavailable. The
first version of the matrices contains as much data as could be collated at the time of writing but
also contains gaps. The later versions progressively employ a variety of techniques to estimate the
missing data. The final matrix, comprising only the foreign born, attempts to reconcile all of the
available information to provide the researcher with a single and complete matrix of international
bilateral migrant stocks. Although originally created to supplement the GMig model (Walmsley and
Winters 2005) it is hoped that the data will be found useful in a wide range of applications both in
economics and other disciplines.