Theories view childhood development as being either driven by structural maturation of the brain or being driven by skill-learning. It is hypothesized here that working memory (WM) development during childhood is partly driven by training effects in the environment, and that similar neural mechanisms underlie training-induced plasticity and childhood development. In particular, the functional connectivity of a fronto-parietal network is suggested to be associated with WM capacity. The striatum, dopamine receptor D2 (DRD2) activity, and corticostriatal white-matter tracts, on the other hand, seem to be more important for plasticity and change of WM capacity during both training and development. In this view, the development of WM capacity during childhood partly involves the same mechanisms as skill-learning.