Between 20% and 57% of patients at community mental health centers miss their first mental health appointment, resulting in wasted resources and longer wait times for other patients. To date, only one peer-reviewed quantitative study examined the relationship between appointment reminder practices and children's and adolescents' first appointment attendance rates for community mental health centers. The purpose of this quantitative study was to examine the relationship between first appointment wait times, electronic appointment reminders, phone appointment reminders, and first appointment attendance for U.S. community mental health centers, along with the potential moderating effects of age, ethnicity, and gender. Blumer's symbolic interaction theory served as the theoretical framework. Secondary data on was collected from 12 Texas-based community mental health centers covering 5,260 patients. Binary logistic regression uncovered the following key study findings: (a) wait time and message type significantly predicted appointment attendance; (b) e-mail appointment and text reminders were significantly more effective than were phone reminders; and (c) age, gender, and ethnicity moderated the relationship between wait time and message type, and first appointment attendance. The implications for positive social change include improving our understanding of the optimal appointment reminder tactics that increase children's and adolescents' mental health appointment attendance rates, improve operating efficiency of community health centers, and increase the likelihood that children and adolescents will receive needed mental health services.