Selective mutism (SM) is a childhood disorder characterized by persistent failure to speak in situations where speech is expected. There is evidence that behavioral interventions are effective for increasing speech in children with SM but studies have been limited by small, relatively homogeneous samples. Although twins appear to be disproportionately represented among children with SM, little is known about their specific treatment needs and barriers to effective treatment implementation in this population. This case study presents family-based behavioral therapy delivered to a set of 8-year-old, identical twins with SM. At posttreatment, both children displayed marked improvements in speaking and social engagement. Clinical considerations for working with twins with SM are discussed.