This study investigated whether the Abandonment schema mediates the relationship between a history of parental separation or divorce and attachment styles in adulthood. Participants (N = 426; M age = 30.78 years) completed online measures, using Qualtrics. Results demonstrated that a history of parental separation or divorce was positively associated with anxious and avoidant attachment styles in adulthood.Mediation analyses revealed that the Abandonment schema mediated these relationships (p < 0.001). This suggests that adults with a history of parental divorce or separation are more likely to report anxious and avoidant attachment styles, and this is partially accounted for by an expectation that they will be abandoned by others.These findings have implications for case formulation and can be used to inform treatment. Schema therapy focused on healing the Abandonment schema could promote attachment security in individuals with a history of parental separation or divorce. For example, limited reparenting (i.e., the therapist seeking to meet the client's unmet emotional needs, within the professional boundaries of the relationship), could be tailored to address the individual's underlying unmet need for security and stability. Further research is needed to advance our understanding of the implications of these findings for treatment.