Two studies investigated the effectiveness of the A-Priori reading intervention program, which uses pre-teaching in an effort to provide at-risk students (who qualify for the Chapter 1 program) with prior knowledge before the regular instruction on the same objectives and topics. In the first study, subjects were a control group of 207 students in the traditional Chapter 1 remedial program and an experimental group of 308 students in the A-Priori program involved in a pilot program in Vermilion Parish, Louisiana. In the second study, subjects were 16 students in a pilot program in St. Landry Parish, who were followed for a 2-year period. Subjects' scores on the California Achievement Test were compared. Results of both studies were similar--no statistically significant differences in subjects' scores were found. Both school districts decided to expand and enlarge the A-Priori program before the completion of the two studies. Teachers and administrators preferred the A-Priori approach. Findings suggest that the A-Priori approach may be valid, but educators should not necessarily expect significant improvement on standardized tests. (Contain 19 references and 5 tables of data.) (RS)