1 Wendy Duncan-Hewitt, Crux Consulting, 1712 Brookwater Circle, Amarillo, TX, 79124, email@example.com 2 David Mount, Crux Consulting, 1712 Brookwater Circle, Amarillo, TX, 79124, firstname.lastname@example.org 3 Steven W. Beyerlein, Department of Mechanical Engineering, University of Idaho, EPB324K, Moscow, Idaho 83844-0902, email@example.com 4 Don F. Elger, Department of Mechanical Engineering, University of Idaho, EPB324K, Moscow, Idaho 83844-0902,firstname.lastname@example.org 5 Judi Steciak, Department of Mechanical Engineering, University of Idaho, Boise, 800 Park Boulevard, Boise, ID, 83712, email@example.com Abstract In the "Information Age," the profession of Engineering needs "critical thinkers" and "complex problem-solvers." Since most entering graduate students do not possess these abilities, it should be the responsibility of graduate programs to mentor their growth in addition to teaching them disciplinary knowledge and sk ills, but this is seldom done. Given that the desired abilities have a cognitive basis, we hypothesize that decisions about appropriate educational methods are best made by considering the development of graduate students' intellectual complexity. A model of intellectual development, the Crux Developmental Model (CDM), was tested for this purpose. The CDM and its application were assessed and improved as a result of use over a three-year cycle in the context of a Science and Engineering Camp in which Engineering graduate students were employed as "Camp Counselors." This paper describes the CDM and its use in the camp. Based on results supporting its efficacy, our recommendations for its broader application in mentoring graduate students, including the use of a developmentally appropriate assessment tool called "The Process Dialogue," are detailed.