Six months after the accident at Three Mile Island in Pennsylvania, McDonald joined an environmental group, the Environmental Policy Institute. McDonald was the director of an energy conservation project at the organization, now called Friends of the Earth (FOE). His primary work included research, media relations, public education, lobbying, and fundraising. Working at FOE piqued his interest in the environmental field and movement. During this time, McDonald also discovered the lack of minority involvement within the field. For instance, in 1979, there were no Black professionals in environmental groups in the Washington, D.C. area. As a result, in 1985, McDonald founded the African American Environmentalist Association (AAEA).

The AAEA was founded on the premise that the lack of diversity in the traditional environmental movement translated into a lack of Black and minority perspectives on environmental issues. Thus, the primary goal of AAEA was to address issues important to minority communities. AAEA worked with local, state, and national leaders on issues like clean air and water – particularly in Washington, D.C. The organization also collaborated with traditional environmental groups that have a presence in the nation’s capital. Collaborations included establishing a water resources program, internships, research projects, publications, and even shared office space. These collaborative efforts and work on other environmental issues expanded McDonald’s perspective on environmental and energy policy. His work allowed him to meet many people, including influential individuals in the environmental movement.

McDonald authored and successfully worked with the U.S. Congress to pass national energy legislation. He presented testimony before federal, state, and local regulatory agencies, U.S. House and Senate Energy and Environmental Committees. McDonald led the fight in Congress in the early 1980s to maintain Corporate Average Fuel Economy (CAFÉ) Standards. He drafted and led the lobbying campaign in the U.S. Congress to pass the Federal Shared Energy Savings Act, signed by President Ronald Reagan in 1986. He also assisted in passing the first civil rights legislation of the 21st Century, the No Fear Act, signed by President Bush on May 15, 2002. He was the author of the first comprehensive pollution studies in Washington, D.C. A recognized national speaker on energy and environmental issues, he appeared in numerous print and electronic media. He has received special recognition from the U.S. Congress, the Environmental Protection Agency, and the Department of Interior. In 2009, McDonald published his autobiography, Diary Of An Environmentalist.

McDonald’s career highlights included working with nuclear power and AAEA’s ability to promote practical environmental solutions, including nuclear power and electric vehicles. McDonald considers his work in the passage of federal energy and civil rights policies his most significant professional achievement. These policies included the Shared Energy Savings Act of 1986, which Ronald Reagan signed, and the No Fear Act, a historic civil rights legislation. His most significant personal accomplishment is being the single parent of a son. His son is the most important person in his life.

While McDonald has accomplished much in the environmental movement, he acknowledged it was very difficult. He found himself unable to build a large organization because of a chronic illness, asthma, and being a single parent. Despite these difficulties, McDonald stuck with a career in the environmental field. He stated that the environment is essential to the survival of the entire planet, which includes minority communities. This thought has kept him an active participant in the environmental field and the movement to encourage greater minority involvement in environmental affairs.