In this study I examine the relationship between environmental attitudes and gender. First, I explore variations across previous studies to determine patterns regarding gender differences in levels of environmental concern. Second, I look at the mediating effects of gender and several socio-demographic characteristics (age, race, class, education, political orientation, residence, martial status, number of children, religious identification, and scientific knowledge) on a variety of measures of environmental concern to assess the extent to which gender operates through other variables as it predicts levels of environmental concern. Third, I look at the moderating effects of gender on the same list of socio-demographic characteristics to determine the extent to which gender intersects with other variables to shape environmental attitudes. I conduct a systematic review of literature using 22 peer reviewed journal articles, which include 128 measures of environmental concern, published between 1995 and 2010. I also test for mediating and moderating effects of gender and various socio-demographic characteristics on 14 measures of environmental concern using data from two sources: the General Social Survey Environment II: 2000 questionnaire and the American National Election Study 2008 Times Series Pre-election Survey. To test for mediating and moderating effects I employee several methodological techniques including principal component analysis, model building, linear regression techniques, and non-parametric regression methods. The results of this study show that, in general, women do express a greater concern for the environment than men. However, gender in conjunction with other socio-demographic characteristics has the potential to produce different effects than when gender is considered alone. This study supports the idea that the intersectionality of gender and other socio-demographic characteristics is of great importance and should not be ignored.