This study examines the emergence of lower-level ESL sentence processing skills involved in integrating English words into predicate structures on-line. The aim of the present study is to examine how the L1 phrase structure and corresponding L1 word integration skills of ESL learners influence their corresponding ESL sentence processing skills in an on-line English sentence reading task. The study examined the English predicate and verb phrase processing skills of a group of Chinese ESL learners whose language has right-branching L1 verb phrase structures (head-complement word order) and a group of proficiency-matched Korean ESL learners whose native language only allows left-branching L1 verb phrase structures (i.e., complement-head word order). The Chinese ESL group (n = 20) was significantly faster than the Korean ESL group (n = 18) in reading and integrating direct object nouns into English predicate phrase structures, though there were no significant differences comprehending the sentences. In addition, the Chinese ESL group was significantly more accurate in reading and comprehending transitive sentences in which the direct objects had an embedded relative clause. The results suggest that L1 word integration skills influence and shape the emergence of on-line ESL word integration