Examinations are conventionally used to measure candidates' achievement in a limited time period. However, the influence of text layout on performance may compromise the construct validity of the examination. An experimental study looked at the effects of the text layout on the speed and accuracy of a reading task in an examination-type situation. A survey of the reading strategies used in examinations was conducted to help in defining the reading context in which text layout may have an effect. A set of guidelines was also derived from research on typographic features of text and these were used to select three text layouts (intended to be more or less legible) from the layouts used in English language reading examinations. Results of the experiment showed that task time was significantly shorter and the number of correct answers per second was significantly higher with the layout conforming to legibility guidelines. Participants' judgements indicated that this layout was also the easiest in which to find answers and the most attractive. The main conclusion of the study is that text layout affects performance in a task that involves reading text to search for specific information in order to answer questions on under time pressure. Consequently, the construct validity of examinations may be compromised by confounding legibility with reading skills.