Undergraduate research experiences are promoted and funded for their potential in increasing students' likelihood of pursuing graduate degrees, increasing their confidence, and expanding their awareness of their discipline and career opportunities. These outcomes, however, depend on the social, organizational, and intellectual conditions under which students conduct research. Large-scale comparative studies suggest that computer science undergraduate researchers participate in fewer of the activities that lead to membership in a "culture of research." This interview-based study illuminates the experiences of both undergraduates and their faculty research mentors in computer science summer and academic year programs. Twenty-five undergraduates and 31 faculty mentors, the majority women, were interviewed. Their stories reveal best and worst case research conditions for students, the special benefits to women who have experienced harassment in their classes, unconscious biases of faculty, the wisdom of faculty who guide undergraduates to successful research outcomes, and faculty's perceptions of benefits for themselves, their departments, and the students they mentor.