[3][4] Maximus was founded in 1975 by David V. Mastran, initially operating as a consulting firm for the federal government, including information technology services.

[8] In 1988, Maximus was awarded its first contract for social welfare from Los Angeles County, and began shifting focus towards business process outsourcing and providing state-based consulting services.

[9] Passage of the Personal Responsibility and Work Opportunity Reconciliation Act (PRWORA) of 1996 under President Clinton granting states greater latitude in administering social welfare programs, and the Balanced Budget Amendment of 1997 amending certain eligibility, enrollment, and beneficiary protections in Medicaid further increased government use of public / private partnerships for the administration of certain program functions.

[17] From 2010 to 2013, Maximus acquired Denver-based Policy Studies Incorporated (PSI) to increase its capacity to serve government clients in the US and expanded into clinical assessment services with the acquisition of Ascend.

[20] In 2018, after twelve years as CEO, Richard Montoni announced his retirement and the company appointed President Bruce Caswell to the position of chief executive officer.

[22] In November 2018, Maximus acquired U.S. Federal citizen engagement center assets from another government contractor (GDIT) for $400 million in cash.

[23] In September 2020, Maximus hired Dr. Arvenita Washington Cherry as Senior Director of DE&I to lead diversity and inclusion activities in its workforce.

[32] In December 2023, US Department of Health and Human Services Secretary Xavier Becerra announced it would be recompeting this contract for the express purpose of inserting a labor harmony agreement.

Some observers, including 17 state attorneys general, noted that there was little precedent for ending an ongoing contract and introducing new labor harmony provisions.

[33] Sen. Bill Cassidy, the incoming chairman of the Senate Health, Education, Labor, and Pensions Committee, stated, 'The Maximus contract should never have ended in the first place,' and expressed concerns that the administration's actions were aimed at promoting unionization among call-center employees.

[46] That same month, Maximus announced a $23.5 million contract with the State of Oklahoma to operate a customer relationship management system for SoonerCare, the state's Medicaid program, and Insure Oklahoma, a program that provides employers with subsidies to help buy private market health insurance for their low- to moderate-income employees.

[60] In 2012, the company launched its first welfare-to-work program in Canada[61] and expanded its Australia operations with a five-year contract to help people with disabilities find employment.

[63] Maximus launched Project NOW (Negotiating Outstanding Warrants), an initiative that collected more than $35,000 to help nearly 100 parents in Shelby County get back on track after missing child support payments.

[65] In 2011, Maximus was recognized as the top performing provider for welfare-to-work services under the United Kingdom's Flexible New Deal programme, helping job seekers into long-term sustained employment.

[66] Following the Flexible New Deal, the United Kingdom government unveiled a replacement program, called the Work Programme, that created welfare reform changes.

[69] In 2012, the company launched its first welfare-to-work program in Canada[61] and expanded its Australia operations with a five-year contract to help people with disabilities find employment.

[84][85][86] Also in 2023, Maximus was rated for the third consecutive year as having one of the 100 best corporate internship programs in the United States by WayUp & Yello[87] and was recognized as a top employer for Gen Z careers in the Handshake 2023 Early Talent Awards.

[91] In 2010, Maximus and other Northern Virginia companies digitized mislabeled and unaccounted-for graves, on a pro bono basis, and upgraded a paper record-keeping system for Arlington National Cemetery.

November 1997- The Hartford Courant reported that Maximus "gets minimal results" when it was hired by the State of Connecticut to manage a child care program for recipients of welfare.

[107] According to the Record-Journal, Maximus "hired too few people, installed an inadequate phone system and fell weeks or months behind in making payments to day care providers.

"[109] December 1998- The Sarasota Herald Tribune reported that the State of Florida had paid Maximus $4.5 Million for a Child Support Recovery contract.

However, the Giuliani administration began to consult with Maximus executives on how the company could "reshape, consolidate and run" the programs, as early as January 1999.

Starting in January, Maximus was awarded contracts worth $500 million, which represented the "largest share" to assess and train as many as 200,000 welfare recipients and to provide job placement.

[115] July 2007- Maximus settled a lawsuit brought against it by the United States government for involvement in falsifying Medicaid claims for $30.5 million.

[116] October 2010- The Los Angeles Times reported that 146 medical workers, including doctors, nurses and pharmacists were allowed to keep working despite failing drug tests.

[120] June 2012- Through an internal privacy audit, Maximus discovered that a worker in Canada illegally viewed personal health records of 43 Canadians.

"[125] Maximus was found to be among the consulting companies that were hired by states—including Alaska, California, Florida, Illinois, Iowa, Nebraska, New York, Maryland, and South Carolina—to locate foster children eligible to receive disability and other checks from Social Security and register them, for the sole purpose of generating revenue for the states.