Undergraduate research opportunities are valued by university faculty and administrators in part because of the belief that they are useful for attracting students to graduate school. Other perceived benefits are that these programs improve students' engagement in their respective disciplines, enhance students' understanding of theory by application to practical problems, and improve students' oral and written communication skills. This study evaluates an eight-week Research Experiences for Undergraduates (REU) program in the Department of Mechanical Engineering at Southern Methodist University to determine how the program influenced participants' perceptions of engineering research and their desire to attend graduate school. The program occurred over three consecutive summers involving students who were selected from a nation-wide pool of applicants. Unlike most retrospective-only, quantitative studies of students who participate in undergraduate research, the current study reports results of before-program and after-program surveys and focus groups conducted on-site. The use of qualitative methods to probe for global and specific attitudes toward engineering research provided a diagnostic element to the analysis that complemented typical learning outcome results. Participants indicated many positive aspects of the REU experience, including an increased understanding of engineering research, how to deal with uncertainty and setbacks in the laboratory, and gaining hands-on laboratory experience. Students said the experience would help them make a more educated decision regarding the pursuit of graduate studies, but in contrast to other published studies it did not necessarily increase their desire to pursue a graduate engineering degree. Positive outcomes of the program appear to be linked to the age of participants, with more positive outcomes associated with more mature students. Implications for managers and facilitators of undergraduate research opportunities are discussed. (Contains 5 tables.)