Visit nonadherence, that is, "no shows," in psychiatry costs the US healthcare $100 billion every year. Nonadherent visits undermine healthcare quality improvement efforts and erode patients' health. Previous research has focused on patient demographics or on redundant scheduling, rather than on the actual structure of visit nonadherence. Drawing on a comprehensive literature review and a series of 3 studies, we identify 22 determinants that contribute to visit nonadherence. Significantly, 8 of these determinants seem to account for most of the variance in modeling visit nonadherence. This work lays the foundation to develop prognostic tools for reducing nonadherent visits in ambulatory care. © 2010 Wolters Kluwer Health Lippincott Williams & Wilkins.