The dramatic growth of the older adult population corresponds with several challenges relating to complex comorbidities of commonly occurring physical health conditions and mental disorders. The ‘Strength and Vulnerability Integration (SAVI)’ theoretical model (Charles, 2010) posits that aging is associated with enhancements in emotional well-being. Unfortunately these emotional enhancements are compromised in the context of a chronic, unrelenting stressor such as a physical health condition and vulnerabilities in emotional well-being are associated with maladaptive physiological changes. Understanding age-related vulnerabilities within this framework, the present research explored the comorbidity of anxiety disorders and physical health conditions longitudinally and mental health service use implications of comorbidities in adults aged 55 years and older. This research specifically focused on arthritis, gastrointestinal disease, and cardiovascular disease. Study 1 examined the bi-directional relationship between individual anxiety disorders and the specified physical health conditions, and further examined sociodemographic and health predictors of incident comorbidities in a longitudinal population-based sample of American older adults. Results provided support for a bi-directional relationship across a 3 year period. Any anxiety disorder and post-traumatic stress disorder were significant independent predictors of incident gastrointestinal disease and arthritis was a significant independent predictor of incident generalized anxiety disorder. Being female and poor mental health related quality of life at baseline were independent predictors of incident comorbid any anxiety disorder and the specified physical health conditions. Study 2 examined the effect of comorbid any anxiety disorder and the specified physical health conditions on past-year mental health service use in a cross-sectional Canadian population-based sample of older adults. Differential relationships emerged across specified physical health conditions on mental health service use with gastrointestinal disease and comorbid any anxiety disorder being associated with lower rates of use. Results have important clinical implications for identification and possible prevention initiatives. The findings are discussed within the context of SAVI and current healthcare practices for older adults.