--- - |2+ Abstract Objective The aim of this study was to examine how accuracy and confidence in working memory performance relates to academic achievement as assessed in the Australian national curriculum assessment (National Assessment Program—Literacy and Numeracy (NAPLAN)). Method A total of 150 Australian schoolchildren enrolled in Year 4 participated in the study. Accuracy and confidence in performance of a working memory task were assessed. Associations between these working memory measurements and scores in each of the NAPLAN domains (numeracy, reading, persuasive writing, grammar, and spelling) were examined, separately for males and females. Results Accuracy in working memory performance was associated with achievement in all five NAPLAN domains, in both males and females. Confidence in working memory performance was also related to achievement, but the pattern of results differed for males and females. For females, significant associations were found between confidence and achievement in numeracy, reading, writing, and spelling. For males, confidence was associated with achievement in numeracy only. Females outperformed males in persuasive writing. There was a non‐significant trend for males to outperform females in numeracy. Conclusion The strong links between working memory and achievement highlight the importance of early detection of working memory problems. Further research is needed to examine the extent to which the pattern of results generalises to other year levels. - Australian Journal of Psychology, EarlyView.