Recent studies have shown evidence of positive concurrent relationships between children's use of text message abbreviations (‘textisms’) and performance on standardized assessments of reading and spelling. This study aimed to determine the direction of this association. One hundred and nineteen children aged between 8 and 12 years were assessed on measures of general ability, reading, spelling, rapid phonological retrieval, and phonological awareness at the beginning and end of an academic year. The children were also asked to provide a sample of the text messages that they sent over a 2-day period. These messages were analyzed to determine the extent to which textisms were used. It was found that textism use at the beginning of the academic year was able to predict unique variance in spelling performance at the end of the academic year after controlling for age, verbal IQ, phonological awareness, and spelling ability at the beginning of the year. When the analysis was reversed, reading and spelling ability were unable to predict unique variance in textism usage. These data suggest that there is some evidence of a causal contribution of textism usage to spelling performance in children aged 8–12 years. However, when the measure of rapid phonological retrieval (rapid picture naming) was controlled in the analysis, the relationship between textism use and spelling ability just failed to reach statistical significance, suggesting that phonological access skills may mediate some of the relationship between textism use and spelling performance.