Health anxiety involves persistent worry about one’s health and is characterized by dysfunctional interpersonal processes such as excessive health-related reassurance-seeking and feelings of alienation from others. Cognitive-behavioral models largely ignore cyclical, interpersonally averse behaviors and social cognitions observed amongst health anxious individuals. The Interpersonal Model of Health Anxiety (IMHA) proposes health anxiety is maintained through activated anxious attachment insecurities, which drive frequent, but ineffective, health-related reassurance-seeking from others. Such excessive health-related reassurance-seeking leads to health-related alienation and beliefs others are unconcerned about one’s perceived health problems. Feeling alienated from others fuels further health-related worry, resulting in continued self-defeating attempts at health-related reassurance-seeking. The present study offers the first comprehensive articulation and test of the IMHA. Using a cross-sectional design and 107 undergraduates, path analysis supported five of six hypothesized paths in the model; all paths except that from anxious attachment to health-related reassurance-seeking were significant and in the expected direction. Specificity tests suggested anxious attachment was more central than avoidant attachment to the IMHA. The present test of the IMHA as a single, coherent model provides a conceptual foundation for future research on interpersonal processes in health anxiety. Clinical implications are discussed.