This report introduces and describes the Unemployment Insurance (UI) program that provides short-term income support payments to eligible persons whose unemployment is caused by circumstances beyond their control.  This report summarizes and critically assesses the relevant UI research conducted since the mid-1970s.  This review is selective, and reflects the author’s judgment as to the most influential work in the field.  The review draws conclusions about the strength of research findings.  It also identifies areas where our understanding is too limited to draw strong conclusions.  Finally, recommendations for further research are offered.