While the share of people under age 65 without a cohabiting partner has been increasing in France since the late 1960s, the duration of these periods of solo living over the life course has never been studied. We calculate the aggregate length of time spent without a cohabiting partner for the cohorts born between 1926 and 1988 using data from the ERFI (2005) and EPIC (2013–2014) surveys, and use linear regressions to identify the factors behind the observed trends. These durations have evolved differently by gender and have shortened for women, who have benefited more than men from the decline in prolonged singlehood and early widowhood. For many years, social origin and educational level structured the length of time spent single, but their effects are progressively weakening. The first baby-boom cohorts (1945–1955) are an exception, having experienced the shortest periods without a cohabiting partner. The increasingly complex partnership trajectories of more recent cohorts thus correspond more to a shift in conjugal norms than to their rejection.