This paper examines sources of gender pay disparity and the factors that contribute to this pay gap. Many researchers question the role of discrimination and instead attribute the residual pay gap to gender differences in preferences. The main issue considered in this paper is whether gender differences in choices, especially with respect to the family and household, are indeed responsible for the gender pay gap, or whether discrimination plays a role. On balance, the evidence indicates that sex discrimination remains a possible explanation of the unexplained gender pay gap. This is consistent with the continuing high profile sex discrimination litigation suggestive of on-going inferior treatment on the basis of sex.