Working Memory Battery (WMB) operationalizes the concept of working memory of Baddeley and Hitch, consisting of three components: phonological loop, visuo-spatial sketchpad and central executive. We hypothesized the existence of a significant correlation of WM with achievement in reading, writing and counting in primary school cycle. The battery will make the difference between masculine gender and feminine gender, between early ages and late ages of the cycle. We used Clinciu Working Memory Battery, consisting of five subtests. WMB is a good expression of working memory, showing a close connection to the criterion of academic achievement in the first school cycle.