The purpose of this study was to determine the extent to which professional development experiences like cooperative education (co-op) may influence undergraduate students' sense of professional identity as engineers. Researchers surveyed 97 baccalaureate engineering students using a modified engineering identity survey first developed by Meyers (2009), which was based on Arnett's (1994) Theory of Emerging Adulthood. Exploratory factor analysis responses generated two factors of identity development explaining 43.8% of the variance among respondents. The first factor (tasks) is composed of tasks students perceive they need to complete in order to become an engineer, while the second reflects behaviors that project confidence in being an engineer (confidence). The task factor showed weak predictive utility in differentiating fifth-year and first-year students and was found to be negatively correlated with the number of academic semesters and co-op experiences completed. The confidence factor did not have any correlation with either metric. Results of the study call for researchers to continue efforts to explore the dimensions of engineering identity and seek to understand the separate and reciprocal effects of classroom learning and co-op work experiences on student identity development. [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/en-US/products/dissertations/individuals.shtml.]