Despite a steady increase in the number of internship programs in educational administration, there is little empirical evidence with which to determine how internships affect both the intern's learning and the mentor-administrator. This paper presents findings of a study that investigated the intern-mentor relationship. The sample included 18 school principals and their 18 interns involved in the University of Connecticut's Administration Preparation Program (UCAPP). Eight mentor/intern pairs were at the elementary level, four pairs were from middle schools, and six pairs represented high schools. Data were gathered over a 2-year period through interviews with the interns and principals, an analysis of taped discussion sessions between interns and their mentors, and analysis of documents. The data suggest that interns undergo five stages of transition--initial contact, liminal, settling in, efficacy, and interdependence. Internships were found to be ideal for acquiring certain types of knowledge: day-to-day understanding of building operations, problem-solving strategies, interpersonal skills, time-management techniques, and reflective thinking. Mentors became colearners as the internship relationship developed, gaining opportunities to critically examine their own ideas, learn new content knowledge, and collaborate on projects. It is concluded that: (1) mentor selection is crucial to interns' indepth learning; (2) mentors need to scaffold opportunities for interns; (3) internship programs should provide internship activities that vary in depth and complexity and link theory and practice; (4) reflection should be an integral part of all internships; and (5) stages of acculturation and sociocultural factors affect how quickly interns adjust to their internship settings. One figure is included. Contains 37 references. (LMI)