BACKGROUND: Being a mother of a young child may be protective against problematic drinking behaviours for some, but not all, women. This paper sought to identify the sociodemographic, mental health, and drinking motive-related correlates of problematic drinking among postpartum mothers. METHODS: Australian mothers with a child under 12-months of age (n=319) were recruited via social media to complete a cross-sectional online survey. Two logistic regressions were run to examine unique factors associated with heavy episodic drinking (one or more days with ≥5 standard drinks) and hazardous alcohol use (Alcohol Use Disorder Identification Test score ≥8) among postpartum mothers, including sociodemographic variables (i.e., age, education, employment, income, relationship status, family size, months postpartum, breastfeeding status, and perceived social support), anxiety and depression severity, and drinking motives.RESULTS: One in 10 (11.6%) mothers reported heavy episodic drinking in the past months and 1 in 12 (8.5%) were drinking at hazardous or greater levels. Older age and more severe postpartum anxiety were associated with higher likelihood of hazardous drinking (OR=1.37, OR=1.09, respectively), while breastfeeding was associated with lower odds of heavy episodic drinking (OR=0.29). Greater perceived social support was associated with lower odds of both heavy episodic (OR=0.56) and hazardous drinking (OR=0.39), while higher coping-with-anxiety and social drinking motives were associated with greater odds of both of these problematic drinking behaviours (ORs ranged from 3.51 to 10.40). Conformity drinking motives were negatively associated with heavy episodic drinking (OR=0.24). CONCLUSIONS: These findings highlight the importance of screening for alcohol problems by health professionals during the transition to motherhood, to identify mothers who may need additional support and preventative care.