This article employs the Luxembourg Income Study (LIS) to compare poverty rates for female-headed households (FHHs) with poverty rates for other households in a number of developed and transitional economies. It then seeks to explain why, in some countries, female-headed households are so much more likely to be poor compared to other families. The next two sections describe the LIS and discuss some of the problems encountered in measuring poverty. The paper then computes poverty rates in individual countries for female-headed households and for all other households using the LIS database. Given the problems associated with measuring poverty, we present several estimates of poverty for both types of household. Two sections then look at two theoretical explanations for the gender poverty gap-human capital theory and a Keynesian approach that emphasizes the importance of fiscal policy as an antipoverty tool. The last section summarizes the main findings and draws some policy conclusions.