The purpose of this research project was to examine theories of learning, theories of teaching, and theories of listening comprehension with a view to developing and testing a computer-enhanced listening comprehension system for English as a Foreign Language within the Thai university system. In addition to carrying out an in-depth literature review, factors contributing to difficulties in the listening process were also carefully examined in order to build a sound foundation for dealing with listening comprehension. A brief history and analysis of Computer Assisted Language Learning were presented together with a review of some computer programs with the aim of determining their characteristics. An Individualized CELL Listening Comprehension Program was then developed on the basis of four theoretical frameworks: the Constructivist approach, the need to use authentic spoken passages, reduction of cognitive load and response to learner differences. The system was then used by twenty students of Suranaree University of Technology (SUT), Thailand for a period of fifteen weeks. Students were volunteers from different proficiency levels. SUT midterm and final examinations were employed, in part, to observe the effect of the program on proficiency levels. The SUT examinations, which were usually in a multiple-choice format, tested students on minor details through short, simple conversations. These tests might not fit entirely within best practice for listening but they seem to be a common way of measuring listening development in several educational contexts. Pretests and posttests examining global ideas and specific details in written and multiple-choice formats were then developed so as to provide a more accurate gauge of improvement in listening skills. Log files were kept in order to scrutinize in detail students� interactions with the system. Questionnaire and interview techniques were applied to seek out students� attitudes towards the program. The results revealed that the participants performed better than their peers in the same proficiency levels in SUT midterm and final examinations although the difference was not at a statistically significant level. However, posttest scores were better than those of pretest at a statistically significant level in most aspects except in case of the global ideas. The log files revealed that all students tended to focus on the word level by attempting to understand and decode every word in the transcriptions. This fixation is likely to explain the low global ideas scores. Analysis was complicated by the fact that some students were not able to use the program frequently enough, usually because of unexpectedly heavy schedules. However, the data extracted through questionnaires and interviews showed that most students demonstrated a positive attitude towards the various features of the program and felt that use of the program had improved their listening skills. In addition to findings relating to the development of listening comprehension, the study revealed that the majority of students felt that they did not think listening comprehension and, more generally the study of English, was sufficiently important to spend time on. This interesting but shocking discovery needs to be attended to immediately as it may have a strong effect on how Thai students prioritize their learning of English, and how this may impact on the levels of proficiency which they might subsequently attain.