Background The aim of the present study was to investigate the following issues: (1) Do students with borderline intellectual functioning have a pervasive pattern of impaired working memory skills across both verbal and visuo-spatial domains? (2) Is there evidence for impairment in executive function skills, and which tasks indicate greater deficits? and (3) Which executive function tasks can effectively identify students with low IQ from typically developing peers? Method Students with borderline intellectual functioning (low-IQ; IQ standard scores were between 70 and 85) were age-matched with typically developing students (IQ standard scores > 95). They were administered a range of working memory and executive function measures. Results The results show that students with low IQ have pervasive working memory and executive function deficits. Specifically, visuo-spatial working memory and the Sorting task were the best single predictors that reliably classified students with low IQ. Conclusions Implications for education are discussed in the context of appropriate diagnosis and support in the classroom.