As the U.S. population ages the number of family caregivers is expected to rise. Family caregivers are a valuable source of informal healthcare services for patients and the public, in terms of reducing healthcare costs. However, research suggests family caregiving is not only financially costly for individuals, but associated with a number of medical and mental health risks, with spouses at higher risk for negative outcomes compared to other family members. Traditional evidence-based therapies for stress in family caregivers have been shown to be minimally efficacious with spouses. No therapies take into account the existential nature of spouse caregiver stress, including the potential nonconscious role of loss of life meaning/purpose and death anxiety. This study of multiple baseline design preliminarily explored the effects of a novel 8-week Terror Management Theory integrated existential psychotherapy (TIE) on stress and nonconscious mechanisms believed to function as buffers for existential anxiety, in five women with spouses receiving cancer treatment. Methods included ecological momentary assessment (EMA) of anxiety and self-esteem states via text message sent three times daily-and intermittent assessment of death anxiety, self-compassion, meaning in life, and quality of life at baseline, intervention, immediate post, and 1-month follow-up. Visual and statistical analyses indicated significant between-phase trend changes in anxiety and self-esteem within participants, although direction of changes varied across participants. Additionally, changes in death anxiety, self-compassion, meaning in life, and quality of life between phases varied across participants in directions inconsistent with intervention aims and participants' subjective impressions of intervention-related changes. Mixed findings point to the complexity of spouse caregiver vi psychology and highlight the need for more effective therapies with this population. Results may also guide future research and development of existentially-informed therapies. vii