This paper presents an information processing model of test anxiety in an attempt to explain the mechanism of test anxiety's effect on working memory within the framework of the American College Testing Program Assessment (ACT). The model suggests that the construct of test anxiety, both worry and emotionality, is represented in the declarative knowledge network as forms of cognitive units. The activation of test relevant and irrelevant information competes within the limited working memory capacity and causes poor performance in highly anxious subjects. About 70 college students of high and low test anxiety, determined through the Test Anxiety Inventory, participated in a series of verbal and visual tasks, and speed and accuracy were determined. Results supported the prediction that test anxiety affected information processing on the verbal analogy tasks, demanding a high load of working memory. The studies demonstrated that the responses of highly anxious subjects may vary according to their perceptions of the situation. Some seemingly contradictory results with regard to homophony judgment tasks are discussed. (Contains three figures, two tables, and five references.) (SLD)