This paper examines the previous studies on “detracking" in the United States，t hat focus on how subject and course choices are made by the students in schools where traditional tracking has been abolished. One of the purposes of this paper is to utilize this information in the context of the course choices of the ]apanese high school students. Using the findings of these studies， 1 compare the situation of comprehensive high schools in the United States with the ]apanese “Sogo Gakka" senior high schools. 1 provide short summaries of the studies regarding the American tracking system. Furthermore，b y introducing policy debates about detracking，1 show that there is a dearth of evidence to enable a choice between the maintenance and the elimination of tracking. By considering previous studies on detracking，1 d emonstrate that“unofficial" tracking continues to exist in schools that should have abolished “o妊icial"tracking and that “unofficial" tracking affects students'subject and course choices. Finally，t he result of the analysis on the situation in American high schools provides us with information that will assist in the study of the course choice in the ]apanese “Sogo Gakka" senior high schools.