The objectives of this research were to determine if the personality traits of instructors at the National Outdoor Leadership School were related to instructor effectiveness as perceived by their students, and to determine if instructor effectiveness was related to changes in the self-concept of students who complete a NOLS course. The research used a pre-treatment/post-treatment· administration of the Tennessee Self-Concept Scale (TSCS) to 355 students in the treatment group, where the treatment was a NOLS course. A control group of 50 students consisted of students scheduled to take a NOLS course. Significant gains in self-concept were found, using ANCOVA analysis procedures, on 7 of the 10 TSCS scales. The only scales not showing significant change were satisfaction, personal self and self-criticism. Instructor personality traits were determined using the Cattell 16PF self-report instrument and by a post-course evaluation instrument which asked for student attributions of instructor personality on a semantic differential scale. Students also rated the overall effectiveness of each instructor on their course. The student effectiveness ratings for the instructors had significant but low predictive ability when regressed against changes in self-concept. The objective 16PE personality instrument produced no significant trait differences between instructors who had effectiveness ratings above the median and those with scores below the median. The 16PF factors, as independent variables, showed significant but low predictive ability on the dependent effectiveness scores. The student-rated personality traits, however, produced very different profiles between high effectiveness instructors and lower effectiveness instructors. The student attributions of instructor personality traits produced an R² of .513 when regressed against effectiveness ratings. The major conclusions from the research were that changes in self-concept do occur as a result of a wilderness skills oriented NOLS course and secondly, that students were able to discriminate instructor effectiveness on the basis of the personality-based teaching behaviors of NOLS instructors. Recommendations for extension of this research .are presented as well as suggestions for research on broader issues of wilderness education and wilderness values. / Ph. D.