An overview is given on the multiplicity of the psychological literature dealing with ambiguity and ambivalence. After an introduction aimed at providing a background with respect to the basic understanding of the two constructs in psychology, various areas of psychological research or ambiguity and ambivalence are described. In regard to ambiguity, research in the following fields is covered: psycholinguistics (lexical and syntactic ambiguity), social psychology (role of ambiguity in person perception, persuasion, helping behaviour, attribution, and norm development), personality psychology (individual differences in tolerance for ambiguity), clinical and abnormal psychology (interpretation of ambiguity contingent on individual differences in anxiety, depression, and aggressiveness), motivational psychology (motive assessment via ambiguous visual stimuli), and organizational psychology (role ambiguity). With respect to ambivalence, more general approaches regarding ambivalence amplification and attitudinal ambivalence as well as more specific approaches dealing with ambivalence over emotional expression, ambivalence as an attachment style, ambivalence with respect to women (ambivalent sexism), and intergenerational ambivalence are discussed.