Purpose: We used a complementary mixed methods approach, grounded in situated expectancy-value theory, to explore the relationship between completing an internship and engineering undergraduate students' preparedness and expectancy of success in obtaining their preferred first position after graduation. We disseminated a survey to institutions in the United States and received 1,583 responses; from this sample, we interviewed 62 students. Design/methodology/approach: Internship experiences are considered among "high impact practices" in higher education. Despite calls to increase the quality and quantity of internships, little is known about relationships between internship participation and how prepared students feel for future work, specifically their first position after graduation. Findings: Our findings showed that the students who participated in internships had positive perceptions of preparedness and expectancy of success compared to their peers. We found that participating in multiple internships was beneficial to these outcomes until a student participated in five internships. After five internships, our data did not show a correlation between increasing numbers of internship experiences and increased preparedness or expectancy of success. Practical implications: While there are benefits to internship participation, after six experiences, additional internships are unlikely to increase confidence in job success and preparation. If that still is lacking, a different approach or conversation on career choice may be warranted. Originality/value: Our findings are unique in identifying (1) the aspects of internships that increase perceptions of success, including tying theoretical concepts learned in the classroom to engineering practice and (2) the point at which further internships do not seem to offer further benefits.