Young adults in Norway mostly choose cohabitation as their first co-residential union and the age of first union formation
is comparatively low. However, dissolution rates are higher in Norway than in most other parts of Europe, potentially leading
to unstable relationship careers in young adulthood. Using recent survey data from Norway on men and women born 1927–73 (N = 9, 723), we analyze the prevalence and correlates of the number of co-residential unions experienced by the age of 35.
We find that the number of co-residential relationships has increased across cohorts, but this development has slowed down
among the youngest cohorts. The type of the first union plays a crucial role, and young adults who did not marry their first
cohabiting partner have a higher likelihood of experiencing several co-residential unions than those who married directly
or via cohabitation.