Research exploring fear of cancer recurrence (FCR) in cancer patients has advanced significantly, resulting in the development of numerous measures, models, and interventions. Comparatively, little research has examined FCR in caregivers. This thesis aimed to (i) compare caregiver and survivor FCR levels (ii) quantify the proportion of caregivers scoring above clinical cut-offs (iii) examine associations between FCR, anxiety and depression (iv) synthesise qualitative research and develop a hypothesis-generating model (v) explore ovarian cancer caregiver FCR (vi) develop a caregiver FCR measure and assess psychometric properties. Study 1 and 2 were reviews using meta-analyses and meta-syntheses, respectively. Study 3 used semi-structured interviews to explore caregiver FCR development, maintenance, and behaviours. In Study 4 qualitative findings informed item generation and psychometric testing was conducted. Meta-analysis revealed 48% of caregivers reported clinically significant FCR. Caregiver and survivor FCR levels were moderately correlated. Strong associations were found between caregiver FCR and depression and anxiety. The review and meta-synthesis found themes unique to the caregiver including fear/uncertainty, caregiver’s role as protector and an overarching fear of losing a loved one. Consideration of the patient’s mortality drove protective behaviours. Caregivers (n= 24) participated in an interview. Inter-related themes included (i) fear/ worry (ii) liminality (iii) hopelessness (iv) caregiver’s protection of the person and oneself. An overarching fear of one’s family member dying explained the relationship between themes. Exploratory Factor Analysis indicated 3 factors: fear of recurrence, fear of progression, and communication. Overall, findings demonstrate unique aspects of caregiver FCR. This thesis provides critical insight into caregiver FCR. An important theoretical foundation to develop and adapt interventions for caregivers is presented.