Abstract Offspring of mothers with mood disorders are known to be at risk for a range of adverse outcomes, but the prevalence of personality disorders (PDs) in this group is unknown. The goal of this study was to assess risk of PD diagnoses and symptoms in offspring of mothers with and without mood disorders, and to explore contributing factors to this risk. This longitudinal study assessed PDs and symptoms of PDs in offspring of mothers with bipolar disorder (O-BD), major depression (O-MDD), and no psychiatric diagnosis (O-WELL) in mid-adolescence and in early adulthood. O-BD were more likely to develop a Cluster B PD than O-MDD or O-WELL in adolescence, and more likely to develop a Cluster B PD then O-WELL in early adulthood. Dimensional analyses revealed that O-BD had elevated symptoms in PDs across all PD clusters at mid-adolescence and young adulthood. O-MDD showed elevated symptoms of antisocial PD at both time points, and of obsessive-compulsive PD at young adulthood. Offspring of mothers with mood disorders, especially O-BD, are at increased risk for PD diagnoses and symptoms in mid-adolescence and early adulthood. Contributing factors to risk of PD symptoms in at-risk offspring are discussed.