The concept of internal versus external locus of control has challenged researchers since its inception in the 1950s and 1960s. Implications of locus of control for student achievement and success in school were the focus for this research. The Rotter Internal-External Scale was administered to 282 high school students in Brandon, Manitoba (Canada). External locus of control was significantly related to grade in school and to the number of credits earned in the first semester of high school. Locus of control did not differ between Natives and non-Natives, between reservation and nonreservation Natives, or by age or gender. One limitation of the study was unmatched sample sizes. Points of discussion included the need to have a successful transition to high school for all students, especially Native students from remote reservations and students at risk. This paper contains 74 references. Appendices list a map of Manitoba, Rotter Scale and instructions, and individual subject data. (TD)