This review paper attempts to update the literature on tolerance of ambiguity (TA) and related concepts since a previous review (Furnham & Ribchester, 1995). Various related concepts like Uncertainly Avoidance and In/Tolerance of Uncertainly are reviewed. Both correlational and experimental studies of TA are reviewed and tabulated. Further, an attempt was made to identify and critique various different questionnaires design to measure TA. Recommendations for the use of these tests in research are made. The reasons for progress and lack of progress in this field are highlighted.