This paper reports on two studies which investigated the relationship between children's texting behaviour, their knowledge of text abbreviations and their school attainment in written language skills. In Study One, 11-12-year-old children provided information on their texting behaviour. They were also asked to translate a standard English sentence into a text message and vice versa. The children's standardised verbal and non-verbal reasoning scores were also obtained. Children who used their mobiles to send three or more text messages a day had significantly lower scores than children who sent none. However, the children who, when asked to write a text message, showed greater use of text abbreviations ("textisms") tended to have better performance on a measure of verbal reasoning ability, which is highly associated with Key Stage 2 (KS2) and 3 English scores. In Study Two, children's performance on writing measures was examined more specifically. Ten to eleven-year-old children were asked to complete another English to text message translation exercise. Spelling proficiency was also assessed, and KS2 Writing scores were obtained. Positive correlations between spelling ability and performance on the translation exercise were found, and group-based comparisons based on the children's writing scores also showed that good writing attainment was associated with greater use of textisms, although the direction of this association is nor clear. Overall, these findings suggest that children's knowledge of textisms is not associated with poor written language outcomes for children in this age range.