American Conservative Union
Established in 1964, the American Conservative Union (ACU) is a large grassroots conservative lobbying organization, committed to a market economy, the doctrine of original intent of the framers of the Constitution, traditional moral values, and a strong national defense. It was formed in response to the electoral defeat of Barry Goldwater; the organizing meeting included Robert Bauman (organizer); Frank S. Meyer, John Chamberlain, Jameson Campaigne Sr., John Ashbrook, Katharine St. George, William F. Buckley Jr. and L. Brent Bozell. Goldwater did not endorse it.
It was modeled after the Americans for Democratic Action, and also was positioned as an organization where members of Young Americans for Freedom (YAF), founded by Buckley, could go when they reached the maximum age of 35. 
Over the years, efforts featured by the organization include fighting to keep the Occupational Safety and Health Administration off the backs of small businesses; opposing the return of the Panama Canal to Panama; challenging arms control treaties; supporting aid to insurgents in communist countries; promoting the confirmation of conservative justices to the Supreme Court of the United States; advocating near-term deployment of ballistic missile defense; and battling against higher taxes and wasteful government spending. It was a major opponent to the 1994 Clinton health care reform proposals.
Since 1971, the American Conservative Union has published an annual "Rating of Congress." Each each member of the House and Senate on a scale of 0 to 100, based on votes cast on a wide range of issues. The ratings are designed to show how members voted on all the major issues in order to gauge their adherence to conservative principles. 
A rating of 100 makes one a "true conservative," while a 0 rating designates a "true liberal". These ratings cover a broad range of issues; the organization mentions more issue-focused rating systems from other conservative groups, including:
- Americans for Tax Reform
- Council for Citizens against Government Waste
- Eagle Forum: values ratings that combine a view of individual liberties with family and free enterprise ideas
- Family Research Council: promotion of Judeo-Christian ideals.
- National Rifle Association
- National Tax Limitation Committee
- National Taxpayers Union
ACU ratings are based on the votes cast by Senators or Representatives on 25 chosen bills. The 2008 ACU ratings for the Senate were based on the votes on the following legislative issues:
- taxes and spending
- HR 5140, a tax rebate bill
- an amendment repealing the 1993 tax increase on Social Security benefits
- an amendment making it more difficult for the Senate to increase income tax rates
- an amendment cutting $750 million from the budget for programs deemed "ineffective" by the Office of Management and Budget (OMB)
- an amendment to halt "pork barrel earmarks"
- HR 1195, an investigation into a $10 million earmark for a Florida road project
- HR 3211, the bailout for Freddie Mac and Fannie Mae
- discretionary spending limit of $1 trillion
- HR 6049, the Alternative Minimum Tax
- stimulus spending
- bailout for the automobile industry
- bailout for the financial services industry
- an amendment to provide additional funding to the Department of Justice to enforce parental notification laws
- an amendment to include the unborn in the State Children's Health Insurance Program (SCHIP)
- an amendment eliminating federal earmark funding for the city of Berkeley, California (U.S. state) in response to Berkeley's city council denouncing the Marine Corps - the ACU considers this "anti-military bias"
- energy and environment
- withdrawal of Iraqi troops (HR 2642)
- farm subsidies (HR 6124)
- Medicare payments to doctors (HR 6331)
- accountability for anti-HIV/AIDS program
- anti-ballistic missile defense program
The ACU ratings tend to be reverse-mirrored by the ratings of Americans for Democratic Action.
- Gregory L. Schneider (1999), Cadres for Conservatism: Young Americans for Freedom and the Rise of the Contemporary Right, New York University Press, pp. 88-89
- Ratings of Congress, American Conservative Union
- ACU, 2008 U.S. Senate Vote Descriptions