The purpose of this investigation was to explore the relationship between working memory (WM) and mathematical problem solving in children with learning disabilities (LD). Children with LD (age 11.5 years) were compared to chronologically age-matched (CA-M) and younger comprehension/computation achievement-matched children (age 8.9 years) on measures of verbal and visual-spatial WM, phonological processing, components of problem solving, and word-problem solving accuracy. The results showed that (1) children with LD were inferior on measures of word solution accuracy, components of problem solving, phonological processing, domain-general WM, and verbal WM when compared to children who were CA-M, (2) children with LD were comparable to younger children on all processing measures, except measures of domain-general WM, visual-spatial WM, phonemic deletion, and identifying problem goals, (3) measures of verbal and visual-spatial WM contributed significant variance to solution accuracy independent of phonological processing, and (4) the influence of WM on solution accuracy was mediated by long-term memory (LTM) processes related to the knowledge of algorithms. The results support the notion that information activated from LTM, rather than phonological processing, mediates the relationship between executive processing and solution accuracy in children with LD.