Although educational attainment is known to moderate immigrant-native wage gaps, the role of the field of study remains largely unexplored. Drawing on detailed data for master's graduates in Belgium (1999-2016), we show that the immigrant-native wage gap narrows over two generations but persists in higher-paying fields (STEM, LEM), while disappearing in lower-paying ones. Wage decompositions reveal a small positive quantity effect (immigrants favour higher-paying fields), outweighed by a negative price effect (as returns to fields are lower for immigrants). This price effect halves across generations. Together, both effects explain 28-37% of the overall pay gap. Sensitivity tests refine these findings.