Approximately 1.4 million nonprofit organizations are registered with the IRS. The figure includes a diverse group of organizations, both in size and mission, which range from hospitals and human service organizations to advocacy groups and chambers of commerce. When compared to other sectors of the economy, the nonprofit sector accounts for 5.2 percent of gross domestic product (GDP) and 8.3 percent of wages and salaries paid in the United States. While these figures shed light on the size and scope of the sector, a complete picture cannot be obtained without considering two critical components of the sector, voluntarism and charitable giving. In 2005, individuals, corporations, and foundations gave $26o billion in charitable contributions to nonprofits and 29 percent of Americans volunteered through a formal organization.