In adults, testing can enhance subsequent learning by reducing interference from the tested information. Here, we examined this forward effect of testing in children. Younger and older elementary school children and adult controls studied four lists of items in anticipation of a final cumulative recall test. Following presentation of each of the first three lists, participants were immediately tested on the respective list, or the list was re‐presented for additional study. Results revealed that, compared to additional study, immediate testing of Lists 1–3 enhanced memory for the subsequently studied List 4 in adults and older elementary school children, but not in younger elementary school children. The findings indicate that the forward effect of testing is a relatively late‐maturing phenomenon that develops over middle childhood and is still inefficient in the early elementary school years. Together with the results of other recent studies, these findings point to a more general problem in young children in combating interference. Testing of previously studied nontarget lists (Lists 1‐3) enhanced recall of a subsequently studied target list (List 4), and reduced number of intrusions from the nontarget lists during recall of the target list in adults and older elementary school children, but not in younger elementary school children.