09-16-2026
International students have long been recognized for their contributions to campus diversity, research and innovation. Yet debates about enrollment often focus on whether increasing international student populations affects opportunities for domestic students.
New research by Town Oh, assistant professor of economics at DePauw University and a Purdue PhD alumnus, offers a nuanced answer: increased enrollment of international students in STEM programs may create greater academic competition for domestic students, but those short-term challenges do not appear to harm long-term career outcomes, and may even strengthen them.
Using student-level administrative data from Purdue University spanning 2008 to 2015, Oh examined how the rapid growth in international student enrollment following the 2008 Optional Practical Training (OPT) STEM extension affected domestic students' academic performance and early labor market outcomes. The policy extended work authorization for international STEM graduates, making U.S. universities more attractive to students from around the world and contributing to a sharp increase in international enrollment.
Rather than asking whether international students help or hurt domestic students, the study published in Research in Laboreconomics, “How International Students Affect Domestic Students' Achievement: Evidence from the OPT STEM-extension,” explores how they influence the learning environment and what higher education leaders can do to maximize the benefits.
Previous research has often attributed challenges associated with international students to language or communication barriers. Oh's findings point to a different mechanism.
International students entering STEM programs tended to arrive with significantly stronger quantitative preparation than their domestic peers. Even after controlling for demographics, course selection and other characteristics, international students scored substantially higher on math assessments (ACT and SAT math) used as indicators of academic preparation.
That difference changes classroom dynamics, particularly in introductory STEM courses where grading is often competitive and students are competing for admission into selective majors.
To isolate this effect, Oh compared the same course taught by the same professor across different semesters while controlling for students' academic backgrounds. This design allowed him to examine how changes in the proportion of international students affected domestic student outcomes while minimizing other influences.
The results were clear: every 10-percentage-point increase in the share of international students in STEM courses reduced domestic students' grades by approximately 0.06 points on a four-point grading scale.
Importantly, this effect appeared almost exclusively in math-intensive STEM courses. Management, English and other non-STEM disciplines showed little or no comparable decline, suggesting the mechanism is increased academic competition rather than communication challenges.
The research found that the greatest impact occurred during first- and second-year STEM "weed-out" courses such as mathematics, physics and computer science.
These foundational courses often determine whether students continue in engineering or other STEM majors. Increased competition from highly prepared peers lowered grades in these courses more than in upper-level classes, where the effect diminished considerably.
One explanation is adaptation. As students progress through their programs, they adjust to the more competitive academic environment while building stronger skills. Another possibility is that students who persist beyond the introductory sequence have already demonstrated the preparation and resilience needed to succeed.
Either way, the findings suggest universities should pay particular attention to supporting students during the transition into demanding STEM curricula.
Perhaps the most important finding of the study is what didn't happen — despite modest declines in grades, domestic students who studied alongside larger numbers of international peers during the period of the study did not experience lower first-year salaries after graduation.
The research suggests that more rigorous academic environments may encourage students to develop stronger analytical skills, persistence and work habits that employers value — even if those gains are not fully reflected in college grades.
For higher education leaders, this distinction matters. Academic performance and workforce readiness do not always move in lockstep, particularly in highly technical fields where employers place considerable value on problem-solving ability and resilience.
The findings offer several practical implications for universities seeking to expand international enrollment while supporting student success:
As colleges and universities continue to expand global engagement, questions about the impact of international students will remain central to institutional strategy.
Oh's research suggests the conversation should move beyond assumptions that international enrollment either helps or hurts domestic students. Instead, international students can reshape the academic environment by raising expectations, increasing competition and encouraging greater effort among their peers.
While that competition may modestly reduce grades in challenging STEM courses, it does not appear to diminish graduates' labor market success and may even help prepare them for increasingly competitive careers in STEM.
For higher education leaders, the challenge is not reducing academic rigor but ensuring students receive the support they need to thrive in it. Done well, growing international enrollment can strengthen both institutional excellence and student outcomes.
Town Oh is an assistant professor of economics and management at DePauw University and a 2022 graduate of the economics PhD program at the Daniels School. His academic advisors were Marge Magner Chair in Economics Victoria Prowse and Professor of Economics Kevin Mumford.
