The fundamental, educational value of internship experience in undergraduate construction engineering education is explored. Analysis of learning outcomes from the structured, construction internships required for the B.S. degree in Construction Engineering and Management at Purdue University are compared with experiential learning theories of Kolb and others, providing a basis for explaining how internship learning "works." The nature and benefits of construction internships which comprise authentic involvement are presented. Students' reported learning experiences are compared to the four modes of experiential learning, concrete experience, reflective observation, abstract conceptualization, and active experimentation. Prevalent learning modes during construction internships are found to be active experimentation and reflective observation, and it is inferred that the dominant learning style in a construction environment is the accommodative learning style postulated by Kolb. Conclusions are drawn based on data from 170 student reports from internship work sites across the country over two years. Important observations include the realization that quality internships enable students to "learn how to learn" in ways that are highly applicable in their future work environments, and that are not otherwise attainable in classroom learning. It is shown that undergraduates are more adequately developed for many demands of their future practice when educators make high-value experiential learning a part of the curriculum.