Background: High-intensity telemedicine has been shown to reduce the need for emergency department (ED) care for older adult senior living community (SLC) residents with acute illnesses. We evaluated the effect of SLC engagement in the telemedicine program on ED use rates. Materials and Methods: We performed a secondary analysis of data from a prospective cohort study evaluating the effectiveness of high-intensity telemedicine for SLC residents. We compared the annual rate of change in ED use among subjects who resided in SLC units that were more engaged in telemedicine services with that among subjects who resided in SLC units that were less engaged in telemedicine and control subjects who lived at facilities without access to telemedicine services. Results: During the study, subjects had 503 telemedicine visits, with 362 (72.0%) in the more engaged SLCs and 141 (28.0%) in the less engaged SLCs. For subjects residing in more engaged SLCs, ED use decreased at an annualized rate of 28% (rate ratio [RR] = 0.72; 95% confidence interval [CI], 0.58–0.89), whereas in the less engaged (RR = 0.962; 95% CI, 0.776–1.19) and control (RR = 0.909, 95% CI, 0.822–1.07) groups there was no significant change in ED use (p = 0.036 for group × time interaction). Conclusions: Individuals residing in more engaged SLCs experienced a greater decrease in ED use compared with subjects residing in less engaged SLCs or those without access to high-intensity telemedicine for acute illnesses. We identified potential factors associated with more engaged SLCs, but further research is needed to understand resident and staff engagement and how to increase it.