The research reported here investigated the relationship between students' use of language learning strategies and their English proficiency, and then interpreted the data from two models in information-processing theory. Results showed that the students' English proficiency significantly affected their use of learning strategies, with high-level students using more strategies more frequently than low-level students. An in-depth analysis of the data revealed that there were some characteristics of strategy use by each group of the students. These characteristics could be linked to five factors in the ACT model (management of L2 learning, imagery, analyzing, practicing and management of information-processing limitations) and three factors in the 3P model (value and expectations concerning achievement, linguistic competence and prior knowledge).