Considerable research has been conducted on the effect of anxiety on academic achievement. The most consistent finding is that high anxiety is associated with low performance, particularly at the elementary school level. To explain this situation, some researchers have hypothesized that anxiety debilitates students' attention span or time-on-task thus negatively affecting their achievement. This study tested that hypothesis. The sample consisted of 91 inner city black students between the ages of 12 and 14. The achievement area was seventh grade reading. Two instruments measured each of the three constructs (academic anxiety, time-on-task and reading achievement). A structural equation model tested the association among the variables. The results confirmed the hypothesized negative association between anxiety and achievement and the positive relation between time-on-task and achievement. When the time-on-task parameter was included in the model the association of anxiety with achievement dropped significantly. This finding is taken as evidence for the importance of time-on-task as a mediating variable between academic anxiety and reading achievement. (Author)