The impact of hiring temporary workers during the tight labor markets of the 1990s was examined through case studies of six hospitals and five automobile plants. The hospitals varied in size from 450 to 6,000 employees. The auto suppliers included unionized and nonunionized small and large companies. The case studies included extensive interviews with human resource directors/managers and analysis of data on employment levels, use of temporary workers, and wage and nonwage costs of temporary and permanent workers by occupation. The data obtained for high-skilled occupations supported the view that employers paid substantially more to agency help to avoid raising wages for their regular workers and to fill vacancies while recruiting workers for permanent positions. The evidence for low-skilled occupations suggested that temporary help agencies facilitated the use of more "risky" workers by lowering their wages and benefits and the costs of firing them. The use of temporary agencies in both high- and low-skilled occupations may have contributed to the stagnant wage growth and low unemployment observed in the 1990s by reducing the pressure on companies to raise wages for existing employees. (Contains 13 references. Information about the establishment-level data collected in the case studies is appended.) (MN)