In this introduction to the papers in this volume, the author argues that the central role of contingent appointees in undergraduate education is beyond dispute, and, yet, the implications for undergraduate learning are very much in dispute. Understanding of this issue and correction of such problems as may exist begin by focusing discussion of contingent appointments on the implications for undergraduate student learning. He states that the impact of the increasing reliance on contingent appointments has been inadequately appreciated primarily because there has been too little attention to its central role in undergraduate, and especially lower-division, general education. The author offers a reappraisal of three relevant issues: qualifications, contribution to student learning, and larger effects. His reappraisal takes account of the differences between the three main types of contingent instructional staff: part-time faculty, full-time non-tenure-track faculty, and graduate assistants. He further reframes the issues in light of additional evidence to emphasize such critical factors as the faculty labor market, faculty time allocations, and the dependence of collegial cooperation on common terms and conditions of employment. The article concludes with some observations regarding future research and institutional policy. (Contains 7 tables.)