This paper offers the first study of job polarization in Great Britain using workplace level data. We document widespread and increasing occupational specialization within establishments, along with substantial heterogeneity in specialization within industries. Changes in the specialization profiles of workplaces account for most of the changes in the aggregate occupational shares between 1998 and 2011. The sharp rise in the fraction of workplaces specializing in non-routine tasks is associated with a large increase in the concentration of non-routine workers in workplaces that specialize in such occupations. We find no evidence of a decline in routine employment among establishments that report the adoption of new technologies, as would be expected from the standard routine-biased technological change hypothesis. Instead, we uncover new evidence that suggests that the increase in non-routine cognitive workplaces is linked to the growth in outsourcing of cognitive tasks.