Molybdenum is known to affect microalloy precipitate evolution during processing in ferrite and austenite, but a unified explanation of the role of Mo in precipitate evolution is still lacking. Experiments and thermodynamic calculations indicate that Mo is incorporated into (Nb,Mo)(C,N) precipitates both in the hot-rolled condition and after reheating to 900 °C. Molybdenum enrichment is reduced after reheating and soaking at 1100 °C. No measurable segregation of Mo to the carbonitride–matrix interface was observed in any condition.