Various factors have been implicated in the development of body image dissatisfaction. Especially important are three constructs: awareness of a thin ideal, internalization of a thin ideal, and perceived pressures to be thin. Using meta-analysis, we calculated the strength of the relationships between each of these constructs and body image, and we evaluated the differences in magnitude across the average effect sizes. We also tested the moderating effects of age and ethnicity, and we compared the average effect sizes with those from meta-analyses of prospective and experimental studies in order to determine whether the effect sizes differed by study design. The results indicated the following: all three sociocultural factors had statistically significant relationships with body image; internalization and perceived pressures have a significantly stronger relationship to body image than does awareness; the effect sizes from cross-sectional studies were significantly larger than those of both longitudinal and experimental studies; and neither age nor ethnicity was a statistically significant moderator of the relationship between awareness and body image or that between internalization and body image. In this article, we discuss the limitations and implications of the findings on future research, theory, and clinical application.