Background: Telehealth has been proposed as an important care delivery strategy to increase access to behavioral health care, especially in rural and medically-underserved settings where mental health care provider shortage areas predominate, to speed access to behavioral health care, and reduce health disparities. Introduction: This study was conducted to determine the effects of telehealth-based care delivery on clinical, temporal, and cost outcomes for behavioral health patients in rural emergency departments (EDs) of four Midwestern critical access hospitals (CAHs). Materials and Methods: Observational matched cohort study of adult (age ‡18 years) behavioral health patients treated in participating CAH EDs from 2015 to 2017 (N = 287). Telehealth cases were matched 2:1 retrospectively to nontelehealth control cases based on gender, age-10 years, diagnosis group, and CAH, before implementation of telehealth in the rural hospitals (2005-2013; N = 153). Results: The greatest number of behavioral health cases evaluated was in the mood, anxiety, and other mental health disorders category. The majority of patients in the telehealth (74%) and nontelehealth (68%) cohorts were 18-44 years. Mean ED wait time for the telehealth cohort was significantly shorter at 12 min (95% CI 11-14 min) (p < 0.001) compared to a mean time of 27 min (95% CI 22-32 min) for the nontelehealth case controls (local provider only). The ED length of stay (LOS) for the telehealth cohort was significantly longer (M = 318 min vs. 147 min, p < 0.001) compared to the nontelehealth cohort. The end of telehealth visit to departure (EOTVtD) from the ED in minutes was evaluated to highlight factors potentially influencing delivery of behavioral health care in the ED. Across three behavioral diagnostic categories, time in minutes from end of telehealth visit to disposition/discharge was significantly longer for suicide and intentional self-injury cases (n = 100; 113 min, 95% CI 88-145; p = 0.004) compared to anxiety, mood, and other mental health disorders (n = 126; 66 min, 95% CI 52-83). There was a clinically meaningful difference in EOTVtD in minutes for substance abuse-related cases, which were shorter in length on average (n = 58; 71 min, 95% CI 54-94). Total ED costs for substance abuse-related cases for the telehealth (n = 58; $4556, 95% CI $3963-$5238) cohort were significantly higher than for the two other behavioral diagnostic groups (p < 0.001). Conclusions: Telehealth consultation in the ED for behavioral health cases was associated with decreased wait time and longer ED LOS. Similar to recent studies, the most common behavioral health cases involved mood and anxiety disorders. Costs related to treatment were highest for substance abuse-related cases, likely due to the additional interventions needed, especially related to resuscitation There are opportunities to improve ED efficiencies and post-telehealth visit protocols related to the timeframe extending from the EOTVtD from the ED, which continues to be a focus of future research. Additio...