This paper explores the earnings return to Catalan knowledge for public and private workers in Cat alonia. In doing so, we allow for a double simultaneous selection process. We consider, on the one hand, the nonrandom allocation of workers into one sector or another, and on the other, the potential selfselection into Catalan proficiency. In addition, when correcting the earnings equations, we control for the correlation between the two selectivity rules. Our findings suggest that the apparent higher lan guage return for public sector workers is entirely accounted for by selection effects, whereas knowl edge of Catalan has a significant positive return in the private sector, which is somewhat higher when the selection processes are taken into account.