One of the most important concerns expressed in A Nation at Risk (National Commission on Excellence in Education, 1984) was being related to how effectively classroom instruction time was being used in America's schools. In response to that report, many concerned educators and community patrons at national, state, and local levels argued that schools should increase the length of the school day and the school year and simultaneously restructure the traditional daily school schedule. The author explored student data from 5 high schools in a large metropolitan area for several years before and after the schools converted to either a Block 4 x 4 or Block 8 scheduling format designed to influence student achievement and success. The author gathered data on measures of student success based on student grade point averages in English and language arts. The author found little evidence to support the hypothesis that conversion to block scheduling formats would significantly affect student achievement in the specific English-content area. Additional support for increased enrollments in English and language arts resulting from scheduling structure changes, as well as for future research on this topic, also are discussed.Key words: block-scheduled high schools, classroom instruction time, impact on student achievement in English and language arts