This paper examines a major social cleavage—sex—in its changing relationship to policy preferences, as this relationship shapes and is shaped by political parties and the partisan attachments of men and women in American society. Some social cleavages come almost pre-packaged in these regards, as with social class and social welfare or racial background and civil rights. Others have less immediate but equally insistent implications, as with religious denomination and cultural values. Though all three leave substantial room for further impacts from political parties and party attachment. Sex is less obvious in its expected relationships. Better data coupled with an analytic framework designed to address the changing relationship between social cleavages and policy preferences by way of partisan attachment allow a fresh approach to sex as a social cleavage in American politics.