The human smile would seem to be among the most straightforward and least ambiguous of emotional expressions, yet it turns out to be one of the most variable and most complex facial displays. This ambiguity has in part contributed to confusion surrounding how best to explain why women appear to smile more than men. A decade ago the first meta-analysis of smiling documented that females smile more than males; moreover this difference was found to be significantly larger in situations involving social tension, and to a lesser extent, when there were variations in the amount of affiliation that was present (Hall & Halberstadt, 1986). As a result, Hall and Halberstadt (1986) concluded that little support was obtained for a dominance-status explanation of the sex difference since no significant correlations were found betweeen the size of the difference and the amount of power or status in the situation. The purpose of the present chapter is to take a second look at these and other potential moderators affecting the gender and smiling relationship by reviewing what is now nearly 20 years later a substantially larger body of research.

Like Hall and Halberstadt (1986), we conducted a meta-analysis of the relationship between sex and smiling. Meta-analyses statistically integrate the mathematical findings of independent research studies and are now considered by many to be superior to qualitative reviews (Cooper & Rosenthal, 1980) and vote counting methods (Hedges & Olkin, 1980) for summarizing research results.