Maguire is Chair and President of Maguire Oil Company and Maguire Energy Company and Chair of Components Corporation of America and Staco Inc. of California. His national leadership positions include serving on The National Petroleum Council, the Executive Committee of Mid-Continental Oil and Gas Association, and as a member of the Madison Council of the Library of Congress, where he funded the Maguire Chair in Ethics and American History.
Maguire's philanthropic efforts also include a grant for the creation of the Maguire Center for Ethics and Public Responsibility and the endowment of a university-wide professorship in ethics at SMU. He has provided additional funds for programs and facilities in SMU's Edwin L. Cox School of Business, including the Maguire Energy Institute, the Maguire Chair in oil and gas management, and the Maguire building housing undergraduate programs in the Cox School. The cumulative total of his gifts to SMU is nearly $9 million.