Ahmanson was born on February 3, 1950. He is the son of Dorothy Johnston Grannis and the American financier Howard F. Ahmanson Sr. (1906–1968). His parents divorced when he was ten years old. Despite the trappings of wealth, Howard Jr. was a lonely child. He has said, "I resented my family background, [my father] could never be a role model, whether by habits or his lifestyle, it was never anything I wanted." His father died when his son was eighteen, and Ahmanson Jr. inherited a vast fortune.
He attended Occidental College, where he obtained a degree in Economics. He then toured Europe, but he returned because of arthritis. He earned a master's degree in linguistics at the University of Texas at Arlington and has fluency in several languages.
In the 1970s, he became a Calvinist and joined R. J. Rushdoony's Christian Reconstructionist movement. Ahmanson served as a board member of Rushdoony's Chalcedon Foundation for approximately fifteen years before resigning in 1996. In 1996, he said he had left the Chalcedon board and "does not embrace all of Rushdoony's teachings." Time magazine included the Ahmansons in their 2005 profiles of the 25 Most Influential Evangelicals in America, classifying them as "the financiers."
Ahmanson's ties as a young man to the Christian Reconstructionist movement and R. J. Rushdoony have been a source of controversy over the years. In an article on the Episcopal Diocese of Washington website attacking the American Anglican Council, Jim Naughton emphasized Ahmanson's ties with Rushdoony. After a $3,000 contribution to Linda Lingle, a Republican running for governor of Hawaii, was returned in 2002, the Ahmansons admitted they had an image problem and let the Orange County Register do a five-part series on them in 2004 to give the public a more accurate view of their work and beliefs. He is reported to have "never supported his mentor's calls for the death penalty for homosexuals"; instead, as the Orange County Register reported in 2004, he "no longer consider[s] [it] essential" to stone people who are deemed to have committed certain immoral acts. Ahmanson also told the Register, "It would still be a little hard to say that if one stumbled on a country that was doing that, that it is inherently immoral, to stone people for these things. But I don't think it's at all a necessity."
In 2004, when asked by Max Blumenthal for Salon if "she and her husband would still want to install the supremacy of biblical law", Roberta Ahmanson replied, "I'm not suggesting we have an amendment to the Constitution that says we now follow all 613 of the case laws of the Old Testament ... But if by biblical law you mean the last seven of the Ten Commandments, you know, yeah." After the initial publishing of the 2004 Blumenthal piece in Salon, Ahmanson wrote a response letter identifying several inaccuracies and assumptions. Salon then published a response with changes made to the original text and addressing some, but not all of the concerns raised by the Ahmansons. Ahmanson has supported certain organizations of the ex-gay movement in that they regard homosexuality as a condition to be dealt with similarly to alcoholism and drug addiction. In 2008, Ahmanson's company, Fieldstead and Company, contributed $1,395,000 to the "YES on 8" campaign according to the Los Angeles Times "Follow the donors" page. Proposition 8, on the California November 2008 ballot, eliminated the rights of same-sex couples to marry.
Howard and Roberta Ahmansons's personal donor organization is Fieldstead and Company, also known as the Fieldstead Institute, an unincorporated entity which has never had a telephone number. Fieldstead does not disclose its finances, but in 2004 they gave the Orange County Register a list of the top 20 organizations they support. In order of the total amount they had given up to that point:Fullhart-Carnegie Museum Trust, Perry, Iowa;
Drew University, Madison, New Jersey;
Discovery Institute, Seattle, Washington;
Claremont Institute; Claremont, California
St. James Anglican Church, Newport Beach, California;
Calvin College, Grand Rapids, Michigan;
American Anglican Council, Washington, D.C.;
Food for the Hungry, Phoenix, Arizona;
Mariners Christian School, Costa Mesa, California;
Ethics and Public Policy Center, Washington D.C.;
Biola University, La Mirada, California;
Orange County Rescue Mission, Santa Ana, California;
Chalcedon Foundation, Vallecito, California;
International Fellowship for Mission as Transformation (INFEMIT USA), Washington, D.C.;
Hudson Institute, Washington, D.C.;
World Vision, Washington, D.C.;
Maranatha Trust, Washington, D.C.;
National Coalition for the Protection of Children and Families (formerly National Coalition Against Pornogoraphy), Cincinnati, Ohio;
Sen USA, Hobart, Indiana;
InterVarsity Christian Fellowship, Madison, Wisconsin
Ahmanson is a major supporter of the Discovery Institute, whose Center for Science and Culture opposes the theory of evolution and promotes intelligent design. Through Fieldstead, Ahmanson's wife Roberta, a former religion reporter and editor for the Orange County Register, has funded and been directly involved with some programs of the Coalition of Christian Colleges and Universities (now known as the Council for Christian Colleges and Universities). These include the Washington Journalism Center, its Summer Institute of Journalism, and its Fieldstead Journalism Lectures. Fieldstead has funded other Christian journalistic projects such as Gegrapha and GetReligion. A common thread in all of these organizations is a personal friend of Roberta Ahmanson's: Terry Mattingly, who directs the Washington Journalism Center at the Council for Christian Colleges and Universities, teaches journalism, and writes a weekly column for the Scripps-Howard News Service. Roberta Ahmanson recently co-edited a book called Blind Spot. The Ahmansons have also supported the creation of the 29-volume Ancient Christian Commentary on Scripture, published by InterVarsity Press.
Ahmanson was the chair of the California Independent Business Political Action Committee (PAC) and later Allied Business PAC. Since the 1980s, he has successfully worked with a small number of conservative businessmen and multi-millionaires, principally Rob Hurtt of Container Supply Corporation, to organize political action committees and increase conservatives' control of the California state government. Ahmanson and Hurtt created the Capitol Resources Institute, which became a major lobbying force for Christian conservatives in Sacramento. The Ahmansons made political donations to the 1993 California school voucher initiative, which failed, and a 1992 voucher initiative in Colorado. Donations from the Ahmansons, Howard's former associate Rob Hurtt and the PACs they are involved with added up to almost $3 million split between 19 conservative candidates and various causes in 1992. Hurtt himself was elected State Senator in 1994 and became chairman of the Republican campaign committee for the State Legislature.
At that time, the GOP was only four seats away from majority control in 1994. This political success has been seen as the result of planning undertaken at the Third Annual Northwest Conference for Reconstruction in 1983 by Wayne Johnson, who, according to The Public Eye, helped craft California's 1990 term limits initiative and "managed the campaigns of several Ahmanson-backed candidates in 1992." The Ahmansons supported Proposition 22, a ban on same-sex marriage in California. Howard Ahmanson contributed $62,500 to the Western Center for Law and Religious Freedom, which, among other things, aided the citizens and leaders of the Kern County school district defend their choice to ban One Hundred Years of Solitude, a book by Gabriel García Márquez, for its "profanity" and "vulgarity." Other Ahmanson political initiatives and their results are discussed in Blumenthal's 2004 Salon article.)
Ahmanson has donated $1,395,000 through Fieldstead and Company to support California Proposition 8 (2008), a November 2008 ballot initiative that would amend the state's Constitution to ban same-sex marriage, which had been legalized in a California Supreme Court case earlier in the year. He had been a six-figure donor to California's previous initiative, Proposition 22. In late 2008, Ahmanson, worried about the narrowing focus of the California Republican Party on lowering taxes, announced that he switched parties and is now a registered Democrat.
Ahmanson was a major force opposing abuses by California redevelopment agencies, especially concerned about the widespread use of eminent domain and public subsidies to private businesses. He financed the publication "Redevelopment: The Unknown Government" and the formation of Municipal Officials for Redevelopment Reform (MORR), along with college friend and Fullerton, California Mayor Chris Norby, in 1995. Norby later served in the California State Assembly when, with Ahmanson's strong backing, redevelopment agencies were abolished in 2011 and MORR was disbanded, having succeeded in its sole purpose.
He has Tourette syndrome. His wife usually communicates with the media and others on his behalf.