Objective:To comprehensively examine weight management practices ina large community sample of women with and without PCOS and theirassociations with dietary intake and physical activity.Design:This study is a large population-based observational cross-sec-tional study (Australian Longitudinal Study on Women’s Health).Setting: Australia.Participants:Women in the 1973–78 cohort (n=7767 total;n=556with PCOS,n=7211 without PCOS).Main outcome measures: Healthy or potentially unhealthy weight man-agement practices, dietary intake and physical activity.Results:Women with PCOS were more likely to be following bothhealthy (reducing meal or snack size, reducing fat or sugar intake or fol-lowing a low glycaemic index diet) and potentially unhealthy weightmanagement practices (smoking or use of laxative, diet pills, fasting ordiuretics) than women without PCOS. For women with PCOS, use of arange of healthy weight management practices were associated withincreases in physical activity, diet quality, % protein and decreases inglycaemic index, % fat, % saturated fat, % carbohydrates or fibre. Use ofpotentially unhealthy weight management practices were associated withdecreases in diet quality.Conclusion:In PCOS, a common condition where lifestyle managementis recommended first line, we report novel findings that community-based women with PCOS are more likely to follow both healthy andpotentially unhealthy weight management practices than women withoutPCOS. Use of healthy practices is generally associated with improveddietary intake or physical activity and use of potentially unhealthy prac-tices is associated with poorer dietary intake. In PCOS we should focuson improving healthy weight practices across both diet quality and quan-tity and on addressing unhealthy weight practices and their potentialadverse effect on dietary intake.