The current study investigates the relation between working memory updating and second language learning (L2) outcomes in typically-developing fourth grade children. Our primary aim was to replicate and extend previous findings on the relationship between updating and low-level reading skills, i.e. fluency. Our second objective was to examine possible updating transfer effects across languages, from the native language (L1) to L2 learning. The languages considered have different orthographic features; shallow for L1 (Italian), and opaque for L2 (English). Mediation analyses were tested using the bootstrapping method; we found that updating was directly related to reading fluency in L2 learning. Moreover, we showed evidence of the mediating role of L1 fluency in the relation between memory updating and L2 fluency. Our findings suggest that updating processes may act at a low level for reading, and are potentially independent from specific language features, both for opaque and regular orthographies.