Forty adult Chinese-speaking learners of English and 20 native speakers of American English participated in a study of second language learners' interpretation of syntactically ambiguous sentences involving "that"-clauses that could potentially be interpreted as complements or as relative clause. Two sentence interpretation tasks suggest that the principle of relevance constrained the interpretations. The learners showed a preference for interpreting the "that"-clause as a complement in the first task, using fewer syntactic nodes because it involved less processing effort. In the second task, however, the learners showed a preference for the relative clause reading, suggesting that the procedural information encoded by preceding referential sentences had the effect of reducing the overall processing effort required and of guiding the second language (L2) learners towards the intended contextual effects.