Based on data from the National Longitudinal Surveys of Youth (NLSY), both male and female workers in larger establishments receive not only higher wages but also have a higher probability of receiving benefits than those in smaller establishments. This phenomenon reinforces the well documented size effect. This study also provides evidence of vast gender differences in estimated union effects on the different components of the compensation structure. Hence unions should not treat both genders similarly with respect to wages and benefits. Specifically, unions may be successful in attracting more female workers to join rank and file if unions could play an active role in making available maternity (paternity) leave, and also provided opportunities for women to join large establishments.