Infant mental health specialists are increasingly expected to treat complex mental health disorders in very young children. Selective mutism is an anxiety disorder which can lead to functional impairment across home, preschool, and community settings. The authors share their experiences with Keylah, a preschooler with significant social anxiety leading to selective mutism in social settings. The intervention included assessment, play therapy, systematic exposure, relaxation training, and interdisciplinary collaboration with community providers.