A study investigated the instructional effectiveness of the Boswell English as a Second Language Program, a phonics-based language teaching program using interactive, multisensory (auditory, visual, tactile) computer technology. The program is a sequence of lessons designed to give non-native speakers an understanding of English phonological structure and its relationship to spelling. Subjects were 10 adult students of varying language backgrounds and skill levels in an intensive English-as-a-Second-Language program, and a parallel control group. Both groups were pre- and posttested using the Basic English Skills Test (BEST) and a Boswell-designed test of the material covered in the program. The experimental group used the system from 24 to 42.5 hours. Test results indicate that the Boswell system had a significant impact on students' ability to recognize and discriminate phonemes as well as on their spelling abilty. However, little correlation was found between time spent using the system and improvement on the Boswell aural test. The experimental group performed better on the Boswell written test but not on the BEST written examination. Students who used the program were generally positive about the system and visibly engaged by it. Students had some criticisms of the program and suggestions for its improvement. (MSE)