Nearly half of U.S. residents are enrolled in employer-sponsored health insurance. Many of these plans use third-party administrators (TPAs), intermediaries—frequently insurance companies themselves—that help build provider networks, design benefit packages, and adjudicate claims, among other responsibilities. But a TPA’s interests may not align with those of their employer clients. CHIR’s Christine Monahan highlights several examples of questionable insurer-TPA practices uncovered in recent years.