Systems thinking is the ability to see the big picture and the related elements when designing, and how these relationships form the big picture. In engineering design, systems thinking is valuable to both industry, as well as engineering education. As such, it creates opportunities for researchers to better understand systems thinking of both professional engineers in industry, who are assumed to be the experts, and engineering students in higher education, who are assumed to be the novices. The purpose of this study was to compare and identify the differences between expert and novice systems thinking in engineering design. Additionally, the study explored the relationship between systems thinking and individual personality. Results from various statistical analysis of 61 teams (18 professionals, 19 seniors, and 24 freshmen) show that professionals are different from senior and freshman students because they focus more on the problem during their systems thinking process, whereas students tend to focus on the solution. Surprisingly, members of professional teams interact less with each other than student teams during the process of breaking down complex problems into smaller and manageable subproblems. The results also showed that there were similarities in systems thinking between professionals and senior students. Additionally, exploratory results from a small subset of the participants show no clear evidence for a relationship between systems thinking and personality traits. Therefore, the existence of the relationship between systems thinking and personality traits remains in question and require further investigation. The findings from this study have several implications for engineering education and future research. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]