ABSTRACT Anorexia nervosa (AN) is a severe mental illness with the highest mortality rate of any psychiatric disorder, with suicide as the second leading cause of death. Despite extremely high rates of suicide, risk factors for suicidal ideation (SI) and behaviors/attempts (SA) in this high-risk population are not well understood. While there is evidence that threat reactivity, stress-response, over-arousal, emotion dysregulation, and agitation contribute to suicide risk, the dynamic relations among these processes have not been characterized on a comprehensive, momentary basis. Our scientific premise, developed from our past work, is that the application of ideation-to-action and network theories will enable the identification of dynamic longitudinal interactions among core dimensions (e.g., arousal, threat), AN symptoms, and SI/SA both between and within individuals. Our study goals are to (1) identify symptom and dimension risk interactions of co-occurring AN and SI/SA between and within persons, (2) differentiate which risk factors predict SI vs SA and (3) test if these risk factors predict onset of SI/SA. These goals will ultimately identify which factors should be targeted in novel prevention and treatment efforts. We will use a multiple units of analysis approach, combined with novel, cutting-edge advances in suicide and network science. We will collect intensive real-time data on AN and suicide behaviors, anxiety, over-arousal, emotion regulation, and agitation using mobile technology, as well as psychophysiological assessment of emotion regulation (via heart-rate variability) and arousal (via electrodermal activity characterizing over-arousal and acceleration characterizing the sleep-wake cycle), from 230 individuals with a diagnosis of AN/Atypical AN (AAN). At 1-month, 6-month, and one year follow-up we will test if individual risk factors predict SI/SA. We expect 35-58 participants will have SA across our study period. The purpose of this supplement is to provide staff support for our research operations and cover additional costs for sensor bands to collect real-time objective physiological data during the 3-week period that participants complete ecological momentary assessment data. This supplement will ensure that we reach our recruitment milestones and collect physiological data in a timely fashion. In turn, this work will help to identify risk factors for the overlap between eating disorders and suicide, which will lead directly to novel prevention and treatment efforts.