Disinhibited attachment behavior (DAB) among infants is persistent and associated with behavioral and relational problems throughout childhood and adolescence. Little is known about risk factors for DAB among infants reared at home, although studies have linked DAB with maternal psychiatric hospitalization and maternal borderline personality disorder. The aim of the current study was to further assess the association between DAB, maternal severe mental illness (SMI; schizophrenia, bipolar disorder, and depression), and maternal PD symptoms. Ninety-three mothers and their infants participated in the study: 46.2% with SMI and 53.8% with no-diagnosis. During pregnancy, mothers were assessed on the Structured Clinical Interview for DSM-5 and the Standardized Assessment of Personality Abbreviated Scale a validated measure of personality disorder (PD) symptoms. Infants were assessed for DAB at 1 year of age using the rating of infant stranger engagement, assessed during the strange situation procedure. Infants of mothers with clinical levels of PD symptoms were significantly more likely to display DAB (OR = 3.44) compared to infants of mothers without clinical levels of PD symptoms. Maternal SMI was not significantly associated with infant DAB. Because most mothers with clinical levels of PD symptoms also had comorbid diagnoses in this study, further work is needed to evaluate the role of comorbidity. These results add to the emerging literature indicating that maternal personality symptoms may be a risk factor for indiscriminate forms of attachment behavior among home-reared infants.