The type of processing–resource allocation (TOPRA) model predicts that increasing one type of processing (semantic, structural, or mapping oriented) can decrease other types of processing and their learning counterparts. This study examined how semantic and structural tasks affect the mapping component of second language (L2) vocabulary learning. Japanese-speaking L2 English learners attempted to map secondary meanings of 24 English homographs. Each participant studied them (a) while making pleasantness ratings about word meaning (mapping plus semantic processing); (b) while counting letters in each word (mapping plus structural processing); and (c) without any additional task (mapping only). Results of L1 (first language) and L2 free recalls and L2-to-L1 and L1-to-L2 cued recalls indicated higher free recall in the semantic condition over the structural condition and higher cued recall in the mapping condition over the semantic and structural conditions, providing qualitatively new evidence for TOPRA model predictions.