The cash-indemnity health insurance system that emerged in the United States after 1945 represented but one trajectory among many. The late 1930s and early 1940s marked a period of innovation and creative experimentation in voluntarist health care programs. Spurred by the Social Security Act of 1935 and the New Deal's legitimization of the politics of security, unions, consumers, employers, and doctors began developing a range of health care programs that enabled patients to pool the risks and costs of sickness and injury, thus bringing medical care within the reach of more people. Employers and private insurers, too, acceded to the pervasive ideology of security. Invoking the New Deal language of security, life insurance companies competed with community and nonprofit organizations to meet a burgeoning market—the market for prepaid health services. While organized labor advocated noninsurance models, commercial insurance companies, aligning with large employers, dramatically expanded their reach during the 1940s, bringing in large groups of subscribers. By the time substantive collective bargaining over health benefits commenced between unions and management in 1950, commercial group health insurance had become well entrenched in many workplaces, and, as a result of this growth, had undercut the competitive and political conditions that enabled other, more equitable, communal-based health insurance alternatives to thrive.