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.