Mirror writing refers to script produced in the reverse direction. The spontaneous mirror writing observed in children may give us an insight into how writing actions develop. However, there is no consensus on whether mirror writing has a predominately perceptual or motor basis. This study aims to address that question, a) 123 children (mean age = 72 months) from an Irish primary school and preschool engaged in tasks designed to examine the relationship between mirror writing and the spontaneous mirror generalisation which enables a child to recognise a letter and its mirror image (Dehaene, 2007). Specifically, they wrote individual lowercase letters and made orientation judgements about these letters and their mirror images, b) 123 children plus 20 adults engaged in novel motor tasks devised to test whether mirror writing was associated with a difficulty in learning actions requiring a specific direction (Della Sala & Cubelli, 2007). A perceptual basis for mirror writing was supported. There was a correlation between letters mirror written and those perceptually confused during the orientation judgement task (rs = .62, p < .01). Mirror generalisations were found to be more frequent than mirror writing for every letter. This suggests that mirror generalisations may be either the causal or limiting factor for mirror writing. A motor explanation was not supported. These findings and their educational implications are discussed.