Born on January 26, 1940, in Decatur, Illinois, into a conservative, deeply religious family, Reilly was strongly influenced by his father, a highway construction steel merchant.

He put priority on elevating attention to the protection and restoration of natural systems, preventing pollution before it is generated, enforcing environmental laws aggressively, and fostering such innovative cleanup technologies as bioremediation.

Reilly played a pivotal role in crafting and securing passage of a new Clean Air bill, enacted by Congress and signed into law by President Bush in November 1990.

[1] Breaking a 10-year stalemate in reauthorizing the Clean Air Act, this law created the first full-scale, fully operational cap-and-trade system as an innovative, market-oriented mechanism to cut sulfur dioxide pollution in half at a time when acid rain was a major environmental problem.

The 1990 amendments to the Act also addressed ozone depletion, established a national permits program for stationary emitting sources, promoted the use of alternative fuels, required major reductions in air toxic emissions, and laid out realistic timetables and commitments to assure steady progress in reducing ozone in cities that have not yet attained air quality standards while increasing EPA's enforcement authority.

While at EPA, Reilly elevated attention to restoring the health of natural systems, including the Chesapeake Bay, the Great Lakes, the Gulf of Mexico, and other water bodies.

Reilly made pollution prevention a priority, negotiating voluntary agreements with industry to reduce toxic emissions and promote energy conservation, and encouraging recycling and waste reduction.

At his direction, EPA did some of the seminal research on greenhouse gas reductions, which helped pave the way for a treaty on climate change, calling for national action plans, periodic scientific and economic reassessments, and assistance to developing countries.

In 1990, Reilly represented President Bush at the opening of the Eastern and Central European Regional Environment Center proposed by the President during his 1989 visit to Budapest (EPA was instrumental in setting up the Center and developing its program); negotiated on behalf of the United States, first in London in 1990, later in Copenhagen in 1992, revisions to the Montreal Protocol phasing out CFCs and other ozone-depleting chemicals; and worked with the Secretary of State and other Cabinet officials on a range of bilateral and multilateral issues involving Brazil, Canada, Hungary, Israel, Mexico, Poland, Russia, Turkey, the so-called G-7 industrialized democracies, and other member countries of the Organization for Economic Cooperation and Development (OECD).

At President Bush's request he led a mission to Kuwait at the conclusion of the war to assess the environmental and health effects of the burning oil fields, and then reported to the Congress on his findings.

He also became the first EPA Administrator to take part in the annual bi-national Cabinet meetings with Mexico, and played a pivotal role in assuring that the North American Free Trade Agreement (NAFTA) factored in environmental concerns.

Later that year, he and his wife moved to the Bay area in California when Reilly accepted the position of Payne Visiting Professor at the Institute for International Studies at Stanford University.

"[8] Appearing on the Diane Rehm Show the same day, congressman Ed Markey (D-MA) responded to the suggestion that an oil industry representative be appointed to the commission by pointing to Republican Reilly's position with Conoco.

[12] In November, 2011, Reilly received[13] the Vincent Scully Prize at the National Building Museum[14] for "his commitment to smart environmental planning, comprehensive land use and preservation of open space".