This study examined operating experiences at 28 sites across the United States at which completed or ongoing groundwater cleanup programs are in place. Although not a representative sample, the sites present a range of the types of cleanups typically performed at sites with contaminated groundwater. At 21 of the sites, pump-and-treat (P&T) systems were used alone as the remediation technology; at two of the sites, permeable reactive barriers (PRBs), an in situ technology, were used alone as the remediation technology. In addition, in situ technologies were used in conjunction with P&T at five sites, including one site with P&T that was replaced with a PRB. Individual reports have previously been published for each of the 28 sites by the Federal Remediation Technology Roundtable. This report summarizes information about the groundwater remediation systems at the 28 sites, including: design, operation, and performance of the systems; capital, operating, and unit costs of the systems; and factors that potentially affect the cost and performance of the systems. Data from the case studies are compared and contrasted to assist those involved in evaluating and selecting remedies for groundwater contamination at hazardous waste sites.