Background: Postponed union formation, declines in marriage, and increases in cohabitation represent major changes in family behavior. The question arises whether these changes have taken place among immigrants and their descendants.

Objective: This study analyzes the integration dynamics across generations of immigrants in France by focusing on partnership formation patterns. It addresses how the socialization vs. assimilation hypothesis shapes immigrants and their descendants’ first partnership formation patterns, analyzing the interplay of cultural and structural factors.

Methods: It compares i) the timing of union formation, ii) the type of first union (cohabitation vs. marriage), and iii) the transition from cohabitation to marriage of first- and second-generation male and female immigrants from the same region of origin with those of the native-born. The data come from the Trajectories and Origins survey (2008) that oversamples immigrants and their descendants. Piecewise-constant exponential models are estimated.

Results: There is a convergence towards prevailing French behavior across the generations of immigrants. Second-generation immigrants form their first union later than the first generation and the level of informal cohabitation increases. Structural factors such as higher level of education have led to changes in partnership formation patterns over generations of immigrants but the convergence is not complete, and cultural factors have a strong effect, especially for women.

Conclusions: Descendants of immigrants have more choices than their parents regarding lifestyle and personal arrangements, and traditional family behaviors weaken. But first unions are still considered to be a long-term commitment rather than a trial period.