In this study, we report the results of two self-paced reading experiments that investigated working memory capacity effects on the processing of globally ambiguous relative clauses by advanced Korean second language (L2) learners of English. Consistent with previous monolingual literature on the processing of temporary ambiguity, we found that working memory capacity was a factor that also affected the processing of globally ambiguous relative clauses. High working memory capacity was positively correlated with a processing disadvantage reflected as slower reading times at the region where the ambiguity becomes detectable, and longer response times to decide on a correct disambiguation for the target structure. Furthermore, a similar pattern was also found in the same participants' processing of L2 ambiguity. We conclude that for highly advanced L2 learners, the processing strategies employed for ambiguous structures are not qualitatively different between the same individual's first language (L1) and L2, but rather differ across readers of different working memory capacities.