Purpose Evaluation of psychosocial concerns, coping style, and mental health in partners of young (diagnosed at ≤40 years) survivors of early-stage breast cancer (BC). Design Cross-sectional; partners participated in a one-time survey. Sample 289 participants; most were male, white, working full-time, college educated, with median age of 43 years, parenting children <18 years old. Methods Logistic regression was used to explore associations with anxiety and depression (≥8 on Hospital Anxiety and Depression sub-scales). Findings Overall, 41% reported symptoms of anxiety, 18% reported symptoms of depression, and 44% identified maladaptive coping. Multivariable regression analyses revealed: lower social support and poorer quality of life significantly associated with depression (p < .05); maladaptive coping, fulltime employment, poorer caregiver QOL, and less education significantly associated with anxiety. Conclusions Partners of young BC survivors who use more maladaptive coping strategies, report less social support, work fulltime, and/or who have lower education levels experience negative mental health outcomes. Implications for psychosocial oncology Enhancing constructive coping and ensuring all partners have access to supportive resources may improve partners’ emotional adjustment.