Employers and employees in France engage in gift exchange practices in the labor contract based on reciprocity. A model called Sequential Reciprocity Equilibrium was used to study how both parties' preferences for reciprocity affect wage differentials. The study found that when both employers and employees value reciprocity, stable gift exchange practices can emerge, leading to non-compensating wage differences across industries and companies. French employers and employees make decisions influenced by their concerns for reciprocity.