New and existing empirical evidence regarding the stock market reaction to strikes is used to test the validity of three strike theories. A review of the existing capital market evidence reveals the need for information regarding the intraindustry announcement effects of strikes against manufacturing firms. This need is filled by applying event-study methodology, in a manner consistent with earlier studies, to a sample of strikes during the period 1982-1999. This new evidence, combined with that of previous studies, consistently supports the validity of Hick's theory that strikes are the result of bargaining errors, misperceptions of bargaining goals, or discrepancies between the expectations of union leaders and the rank and file.A CONSIDERABLE EFFORT HAS BEEN GIVEN TO EMPIRICAL STUDIES OF THE DETERMINANTS of labor disputes. Unfortunately, even the most careful econometric analyses have difficulty in discriminating between alternative hypotheses regarding the causes of strikes. This is so because the variables available in most data sets can serve only as imperfect proxies for the variables hypothesized to influence the probability of strikes, with the result that estimated relationships often may be interpreted in ways that are consistent with more than one theoretical framework. Studies of the stock market response to labor disputes provide more promising 80 The authors' affiliations are, respectively, Kutztown University of Pennsylvania and Lehigh University.