This study provides new evidence on the industrywide impact of strike by investigating how strikes have affected the values of struck and nonstruck airlines. Using stock market data for the years 1963-86, the authors show that most strikes adversely affected the value of struck airlines' stock, but enhanced the stock value of nonstruck carriers. The results also show that strikes before October 1978, which marked the end of strict regulation of the industry and of the employers' mutual aid pact, had some effects different from those of strikes after that date.