This book presents comprehensive and rigorous research on the acquisition of Chinese negation by L1-English and L1-Korean learners within the theoretical framework of the Interface Hypothesis and the Feature Reassembly Hypothesis. The results from grammaticality judgment data (N=182) and learner corpus data (overall scale: 15.19 million characters) reveal multiple factors contributing to the variability in L2 acquisition at the interfaces involved with Chinese negative structures, including L1 influence, the quantity (input frequency) and the quality of the target input (input consistency and regularity), as well as L2 proficiency. These factors also underlie the detectability and reassembly of the [±realis] features encoded with bu and mei, the two primary negation markers in Mandarin Chinese, in different licensing contexts. Task modality (written vs. aural) seems to play a role in L2 learners' access to explicit and implicit knowledge about Chinese negation, but the effect of task modality is constrained by other factors such as structural/feature complexity, L2 proficiency, and L1-L2 similarity. The approach of employing both elicited experimental data and authentic learner corpus data furnishes new evidence for the acquisition Chinese negation by L2 learners. The findings of this study are of significance to the examination of the Interface Hypothesis and the Feature Reassembly Hypothesis in generative-oriented SLA research.