The goal of the current research was to study the cognitive processes that support the emergence of writing in young children and to ascertain whether working memory, language ability or motivation to write underlined children's early attempts to learn how to write. Working memory, language ability and the emergent writing skills of 30 Irish children were tested, in a longitudinal study over a three year period, starting at ages 4 to 5 years in their first year of formal education. A cross-sectional study of 31 children in Junior Infants and 13 children from both Senior Infants and First Class was also conducted. Working memory was tested using the Automated Working Memory Assessment (AWMA). Tests of letter names and sounds, morphological knowledge/ grammar were administered. The children completed free writing tasks and writing output was analysed for linguistics features (e.g. spelling errors) as well as creativity, originality and task relevance. Children rated their liking of writing as an index of motivation to write. The results showed that working memory was associated with the originality of children’s emergent writing, as well as structural aspects of writing, particularly the use of connectives. Verbal working memory played a key role in particular. Participants’ early knowledge of grammar and sounds was associated with fewer orthographic errors in early writing and also with later measures of originality and detail. Children’s liking of writing had a more modest effect. Gender differences, contrary to expectations, were absent; however, trends in the data suggest differences that might have emerged at older ages. These findings highlight the complex interactions of language and memory functions in supporting early writing.