Background: Children with learning disabilities are identified by their severe learning problems and their deficient school achievement. On the other hand, children with sub-average school achievement "and" sub-average intellectual development are thought to suffer from a general intellectual delay rather than from specific learning disabilities. The open question is whether these two groups are characterised by differences in their cognitive functioning. The present study explored several functions of working memory. Method: A working memory battery with tasks for the phonological loop, the visual-spatial sketchpad and central executive skills was presented in individual sessions to 27 children with learning disabilities and "normal" IQ (ICD-10: mixed disorders of scholastic skills), 27 children with learning disabilities and "low" IQ (intellectual disabilities), and a control group of 27 typically developing children with regular school achievement levels and normal IQ. Results: The results reveal an overall deficit in working memory of the two groups with learning disabilities compared with the control group. However, unexpectedly, there were no differences between the two groups of children with disabilities (normal vs. low IQ). Conclusions: These findings do not support the notion of different cognitive functioning because of differences in intelligence of these two groups. In the ongoing discussion about the role of intelligence (especially as to the postulated discrepancy between intelligence and school achievement in diagnosis and special education), our findings might lead to rethinking the current practice of treating these two groups as fundamentally different.