Selective Mutism is a low incidence disorder but has considerable impact on the school system when it occurs. Over the last decade several research articles have been published which have challenged the understanding of the aetiology of Selective Mutism. Current perceptions about the aetiology of Selective Mutism are considered in order to inform the practice of educational psychologists (EPs). Research suggests a multifactorial aetiology with evidence of co-morbidity. Hypothesis led suggestions are made about assessment and intervention of Selective Mutism. (Contains 1 table.)