Thanks to direct access to union databases, this paper applies survival analysis to a sample of 47,637 Italian workers trying to explain the determinants of the duration of union membership. The results show that union membership duration is a positive, though declining, function of age.
Furthermore, women, flexible workers, foreign ones and those working in cities tend to show less attachment to union membership than other workers. The estimated median duration is about six years. Positive hazard duration dependence is also found. Unobserved heterogeneity is
detected but it does not significantly affect model estimates.