Mills has been a leader in many arts and civic organizations throughout his educational career and into retirement.

Some of his leadership roles included:

• Charter Member, Board of Directors and Director of Research, National Council of Art Administrators
• Consultant, Harvard University Latin American Fulbright Scholarship Program
• Member Board of Directors, National Art Education Association
• Member, National Alliance for Arts Education/ Kennedy Center
• President, Western Arts Association
• Inaugural President, Illinois Alliance for Arts Education
• President, Indiana Art Education Association
• Chairman, Illinois Task Force for Arts Education
• Member, Tennessee Arts Commission
• Member, Research Committee for the National School of Art and Design
• Resource Person, Arts, Education and Americans Panel of the Rockefeller Study
• Charter Vice President, Board of Trustees, Illinois Summer School for the Arts
• Trustee, Hudson Area Library District
• Co-Chair, Major Gifts for the Normal Theater Restoration Project
• Sponsor, Illinois State University Scholarship for Outstanding Senior in Art
• Sponsor, Skilled Craft Awards for the McLean County Art Association