This study examined reading performance of 102 Chinese Mandarin-speaking 4th graders in their second language (L2, English) as a function of performance in their first language (L1, Chinese). The results revealed that for Rapid Automatized Naming (RAN) and Rapid Alternating Stimulus (RAS) measures, the mean naming time decreased monotonically in high-achieving, average, and low-achieving readers. RAN and RAS differentiated poor readers from good and average readers but failed to differentiate between good and average readers. RAN deficits occurred in poor readers in both languages. Comparison of memory profiles revealed that patterns varied depending on the mode of stimulus presentation or response. Low-achieving readers performed poorly on a subtest involving visual components only and did relatively better on a subtest involving verbal components only. Poor readers in Chinese also encountered difficulties in learning English as a L2. RAN-character accounted for unique variance in two Chinese reading measures. RAN-letter explained unique variance in English mid-term reading grade. The unique variance captured by the Color Span Subtest 1 (visual-visual) was found in Chinese reading comprehension but not in English reading comprehension. Reading performance in L1 was predictive of reading performance in L2 and vice versa.