In the post-World War II period, wage and price levels reacted much less to business contractions than they did in earlier times. Inflation prevailed and its persistence increased. The contractions themselves became relatively short and mild. All these developments have some common roots in the major structural, institutional, and policy changes of the era. This paper takes a look at the assumptions concerning wage and price behavior in types of contemporary macroeconomic theories and their implications for the analysis of the business cycle. The various hypotheses of real and nominal "rigidities" are then related to each other and to alternative theories of how markets clear. Long-term stable wage and price arrangements or contracts have i...