In 2000 and again in 2001, the Southern Regional Education Board (SREB) conducted an audit of course-taking patterns by a total of 4,244 graduating seniors from 51 rural high schools in 12 states. Each school provided data on a random sample of 100 seniors, including special needs students unless they required accommodation for participation in state standardized tests. At least 90 students in each 100 of the sample must have completed the High Schools That Work achievement tests in reading, mathematics, and science and the student survey, or the school was dropped from the study. The baseline assessment data from both years provide evidence that the one change in school practices that can have the greatest impact on student achievement is to have every student complete a challenging academic core and either an academic or career/technical concentration. This change is effective regardless of students' racial and socioeconomic backgrounds. The 13 rural high schools with the greatest proportion of students completing the recommended academic core had significantly more students with mean achievement scores at the proficient or higher levels and significantly fewer students at the below basic level in reading, mathematics, and science as measured by the National Assessment of Educational Progress. (SLD)