This chapter reviews the past history and conceptual development of burnout and discusses its current status, both theoretical and empirical. The diversity of burnout causes, symptoms, definitions, and consequences has contributed much to the confusion about the specificity of burnout. Burnout first emerged as a social problem, not as a scholarly construct. Thus, the initial conception of burnout was shaped by pragmatic rather than academic concerns. Later on, there was a second, empirical phase, in which the emphasis shifted to systematic research on burnout and in particular to the assessment of this phenomenon. Standardized measures of burnout were developed, thus providing researchers with more precise definitions and methodological tools for studying the phenomenon. In particular, the development and widespread acceptance of the Maslach Burnout Inventory (MBI) and the Tedium Measure (TM) fostered systematic research on burnout, resulting in an increased number of articles published in scholarly.