Exploiting the richness of the Danish register data on individuals and companies, we are able to provide an overall assessment of the assortative matching patterns arising in the period 1996-2005 controlling for firms and individual characteristics. We find strong differences between men and women in assortativity. While positive assortative matching in job-to-job transitions emerges for good female workers, good male workers are more likely to be promoted. These differences are not present in female friendly firms which have high profits and where good female workers tend to find jobs. Complementary analysis on job-to-unemployment and job-to-self-employment transitions reveals a lower employer's willingness to retain women. Overall, we find strong evidence of glass-ceilings in certain firms preventing women to climb the carrier ladder and pushing them to look for better jobs offered by more female friendly firms.