It has often been observed among teachers of English as a foreign language that the English article system is difficult for learners to master. This paper provides a processing account which pinpoints the source of these errors as being within the learner's architecture for production. We illustrate our account with a computational model of one group of foreign language learners embedded within NL-Soar. The model's control structure and learning mechanism are used to explain the architectural character of errors and to predict the conditions required for overcoming them.