This study investigated the interactions between two types of feedback (implicit vs. explicit) and two aptitude components (language analytic ability and working memory) in second language Chinese learning. Seventy-eight L2 Chinese learners from two large U.S. universities were assigned to three dyadic NS–NNS interaction conditions and received implicit (recasts), explicit (metalinguistic correction), or no feedback (control) in response to their non-target-like oral production of Chinese classifiers. The treatment effects were measured by a grammaticality judgment test and an elicited imitation test. The Words in Sentences subtest of the MLAT was used to measure language analytic ability; a listening span test was utilized as the measure of working memory. A principal components analysis and a structural equation modeling analysis established that working memory was an aptitude component. Multiple regression analyses showed that language analytic ability was predictive of the effects of implicit feedback, and working memory mediated the effects of explicit feedback; all the statistically significant results involved delayed posttest scores. Interpretations were sought with recourse to the mechanisms of the cognitive constructs and the processing demands imposed by the different learning conditions.