Background and Purpose: Mirror viewing is a central concept in body image, as many feelings and thoughts about one's body originate in the mirror. The Mirror Image Comfort and Avoidance Scale (MICAS) is a self-reported instrument to assess the experiential aspects of mirror viewing. The development of this instrument is grounded in the nursing mid-range Neurocognitive Mirror Comfort and Avoidance theory. This study aimed to validate the MICAS in a general population, explore its subscales, and note demographic differences. Methods: Waltz, Strickland, and Lenz's instrument validation framework guided the process. A survey website was used to recruit adult participants ( n = 205). Convergent validation was established by assessing the relationships between mirror comfort and avoidance scores and measures of anxiety, depression, stress, self-esteem, and body appreciation. Results: Validity was obtained, and the subscales were reliable. Cronbach's α score was satisfactory for comfort at .90 and avoidance at .92. Significant associations were found between mirror comfort and avoidance and all psychological variables, indicating that mirror comfort and avoidance play a role in body image and overall well-being. Conclusions: MICAS is a nurse-developed instrument designed for research purposes to enhance our understanding of mirror viewing and formulate supportive nursing interventions to improve the mirror viewing experience.