OBJECTIVE: The purpose of this study was to report the distribution of pelvic support among a population-based sample of middle-aged community-dwelling women, as defined by pelvic organ prolapse quantification (POP-Q) and study factors that might influence POP-Q measurements. STUDY DESIGN: We conducted a secondary analysis of a population-based study of community-dwelling, African American and white women aged 35-64 years from southeastern Michigan. Three hundred ninety-four women consented to physical examination using the POP-Q, Statistical analysis included descriptive statistics and multivarlable regression. Estimates were weighted to reflect probability and nonresponse characteristics of the sample to increase general zalbility of the findings. RESULTS: The following values were the mean values for POP-Q points: Aa and Ba = -1,2 cm, C = -6.5 cm (intact uterus), C = -6.9 cm (hysterectomy), and Ap and 3p = -1.8 cm. The POP-Q stages were organized in the following manner: stage 0, 8.8% stage 1, 21.4% stage 11, 67.7% stage 111, 2.1%. Increasing vaginal parity was associated with increasing descent of the anterior, apical, and posterior vaginal wall (P<.001). CONCLUSION: In this population-based study of women from southeastern Michigan, 90% of the women had anterior and posterior vaginal wall support that was above or extended to the hymen. Increasing vaginal parity was associated with increasing descent of the anterior, posterior, and vaginal apex.