A study used schema theory as a basis for developing an instrument to evaluate reading software. The instrument was designed to assess software used in English-as-a-second-language (ESL) reading instruction. Evaluation criteria and questions were developed to address the programs' interactive capabilities (flexibility, response to student errors, and ability to distinguish between significant and insignificant errors), approach to information processing (encouragement of the use of prediction and problem-solving strategies, use of text-based activities in the context of a reading passage, and encouragement of textual analysis skills for comprehension), approach to background knowledge (assumption of existing knowledge, and the building of schemata through pre-reading activities), and general software construction and use. The instrument was then used to examine a sampling of four current software packages. The results of the evaluations are presented, and the advantages and limitations of the instrument are discussed. (MSE)