It is argued in many circles that a structural change occurred in U.S. collective bargaining in the 1980s. Strike incidence declined, dispute incidence increased, and the composition of disputes shifted away from strikes and toward holdouts. We investigate the extent to which the hiring of replacement workers can account for these changes. For a sample of over 300 major strikes since 1980, we estimate the likelihood of replacements being hired. We find that the risk of replacement is lower for bargaining units with more experienced workers, and declines during tight labor markets.