Undergraduate engineering students' self-efficacy beliefs - their perceived confidence in their abilities to complete the tasks that they deem necessary to achieve a desired outcome – have repeatedly been linked to their achievement, retention, and interests in the field. Understanding what these students' efficacy beliefs are and how they are influenced by the engineering environment has thus become the focus of many engineering education researchers. The study reported here used a combined quantitative and qualitative survey instrument to investigate undergraduate chemical engineering students' self-efficacy beliefs during their first required chemical engineering-specific course, Chemical Engineering Calculations (CHE 205). Surveys were administered to all students enrolled in the course during the fall and spring semesters of the 2005-2006 academic year. Quantitative measures were used to evaluate students' perceptions of their performances on course tasks and their ability to succeed in the class. Open-ended survey questions prompted the students to list aspects about CHE 205 that affected their confidence in success in the course. Results presented here are based on the findings of a comparative investigation looking at the effect participation in a cooperative education program and instructional methods may have on chemical engineering students' efficacy beliefs. Findings suggest how the chemical engineering environment, curriculum, and classroom practices might influence students' self-efficacy, a significant factor to be considered in attempts to boost both the retention of capable students who are considering leaving the program and the performance, satisfaction, and enthusiasm of those who persist.