This paper focuses on the impact of unionization on involuntary job loss using establishment data from the 1997 National Employer Survey (NES-II) and merging those data with contextual data at the industry level as well as with local labor market data. The estimated logit models included information on unionization rates and employment security provisions present in collective bargaining agreements as factors influencing layoff rates for individual establishments, controlling for establishment size, firm structure, use of non-regular employees, product/service demand and local employment. Results show that the impact of unionization is not significant except for (1) establishments that operate in the non-manufacturing sector; and (2) establishments operating in industries that have major collective bargaining agreements which contain moderate employment security provisions. Under those conditions, unionization decreases layoff rates; otherwise, unionization has no effect on layoff rates. These results provide some evidence that unions may have placed increased emphasis on employment security in order to protect members against involuntary job loss. This is in contrast to earlier studies which found a positive relationship between unionization and layoffs. In addition, establishments in Right-to-Work states have higher rates of involuntary job loss.