When we focus on men's and women's health, sex and gender are important considerations. Yet, there is often a lack of consistency in the use of these concepts in the research literature (e.g., sex and gender are often used interchangeably). Although limitations inherent in current conceptualizations of sex and gender have been recognized, sex and gender are interrelated but distinct concepts . Gender is a social construct, a multidimensional determinant of health that intersects with culturally prescribed and experienced dimensions of femininity and masculinity, and emerges in diverse individual health practices.Sociologists have conceptualized gender as plural (we speak of femininities and masculinities), context specific, and changing over time and history. For instance, codes of femininity in the Victorian era have given way to more diverse femininities in the 21st Century. Sex, on the other hand, is a biological construct often thought of as a binary (female and male); however, variations within and across males, females, and transsexual individuals in relation to anatomy and physiology point to a continuum of sexrelated characteristics. Lorber (1996) also reminded us that sex and gender (and sexuality) are not necessarily fixed nor congruent-that is, being female does not always correspond to being feminine, and individuals may exhibit a range of genders/sexualities over time. Social aspects of gender can also influence biological processes. For example, the feminist movement resulted in the widespread availability of the contraceptive pill, making pregnancy a choice for women rather than a biologically determined outcome, and this has contributed to reductions in maternal morbidity and mortality. Inversely, biological processes may influence gender identities. For example, Viagra is the biggest selling male pharmaceutical, and by virtue of its vasodilation properties, the "blue" tablet affords increased erectility, which some men experience as affording them purchase of masculine ideals around virility and sexual performance (Baglia, 2005;Potts, 2005).Descriptions of health and illness differences between men and women abound in the literature. For example, men are more prone to die from circulatory diseases than women in all Organisation for Economic Co-operation and Development (OECD) countries (OCED, 2006). Women experience a heavier burden of chronic disease.Men's and women's use of the health care system differs, and they often respond to services and therapeutic interventions in diverse ways. This evidence, although important, is largely based on studies of sex differences between men and women (or girls and boys), and offers only glimpses of the influence of gender. Moreover, researchers conducting these studies have a tendency to treat men and women as all-encompassing groups, and the byproduct of this can be that the diversity within and across these two groups is missed. Of particular concern in studies of men's and women's health is that gender and sex are often erratically incorporated into res...