Previous research on cross-linguistic transfer has provided evidence about the transfer of reading performance and strategies. However, little knowledge exists regarding how motivational factors (e.g. self-efficacy, intrinsic motivation [IM], extrinsic motivation [EM]) transfer and how they facilitate the transfer of reading from the first language (L1; i.e. Chinese in this study) to the second language (L2; i.e. English in this study). Furthermore, there is little agreement on the relationship between self-efficacy, IM, EM, and reading comprehension in L1 and L2 studies. This study aimed to (1) explore the relationship between self-efficacy, IM, EM, and reading comprehension in both L1 and L2; (2) identify whether self-efficacy, IM, EM, and reading performance can be directly transferred from L1 to L2; (3) and investigate how self-efficacy affects the cross-linguistic transfer of reading comprehension. 2,894 fourth-graders from 38 Hong Kong schools participated in this study. Results found that the relationship between self-efficacy, IM, EM, and reading comprehension was consistent in both L1 and L2. For cross-linguistic transfer, IM, EM, and reading performance can be transferred directly from L1 to L2, but reading self-efficacy cannot. Findings also indicated that self-efficacy indirectly affected L2 reading through several potential pathways. Implications for bilingual reading education are discussed.