Abstract

This interlanguage study was aimed at an investigation of sixty Thai EFL students’ acquisition of English prepositional relative clauses, also known as object-of-preposition relative clauses (OPREPs). The participants of the study, equally divided into two groups of high- and low-proficiency levels, were asked to do a sentence-combination task where two simple sentences would be merged into one complex sentence containing an OPREP or a related adverbial construction introduced by where. The research findings indicate that Thai learners seem to produce the null-prep construction, which is ungrammatical in the target language, in the early stages of OPREP acquisition. As their proficiency increases, the amount of null-prep use gradually declines. In addition, they apparently acquire the preposition stranding prior to the pied-piping structure, the latter of which is less salient in L2 input. The results of the present study lend support to several previous studies in order of OPREP acquisition.