One of the sharpest criticisms of welfare state research is insufficient attention to factors relating to gender relations and inequalities. Recent scholarship has begun to address welfare state effects on gender-related outcomes, but the evaluation of theories of welfare development with respect to gender factors is somewhat less developed, leaving open a number of important questions regarding gender as a mechanism behind welfare state development. Using established theoretical perspectives as a baseline model, this study evaluates the effects of women s political power on welfare state effort within 12 capitalist democracies. Cross-sectional time-series analyses of OECD data provide evidence for the impact of women's political representation on levels of social expenditure. Further, women's political representation mediates a portion of the effects of women in the labor force. We discuss implications for extending welfare state theory and for refining the role of gender-related mechanisms in welfare state development.