The aim of this study was to examine the development of working memoryʼs components and their relationships. Phonological loopʼs, visuospatial sketchpadʼs and central executiveʼs efficiencies were assessed by simple and complex span tasks and executive tasks with verbal and visuospatial material. The analyses were performed on 64second-grade and 55 fifth-grade childrenʼs data. Developmental performances improvement was examined according to tasks and material. Analyses of variance revealed performances improvement according to age and type of material (verbal>non verbal) for the slave system tasks and for a part of central executiveʼs tasks. Correlation analysis and exploratory factorial analysis suggested that slave systems would become progressively more specific and that central executiveʼs efficiency would be dependent on this specialization.