New York — Cary Nelson, president of the American Association of University Professors, challenged higher-education unions to “lead the charge for social justice” during his keynote speech here at an annual conference of faculty-union leaders and college administrators.

“Many unions don’t understand their larger cultural role,” Mr. Nelson, an English professor at the University of Illinois at Urbana-Champaign, said in a lunchtime address to about 250 people. “A faculty union should be a source of public inspiration and solidarity. We need to envision a day when people outside the local look at a faculty union with admiration.” He spoke at a meeting of the National Center for the Study of Collective Bargaining in Higher Education and the Professions.

Unions are also grappling with how to get younger faculty members more engaged as members, Mr. Nelson said later, in an interview. “You have to reach out to younger faculty with something that will appeal to them,” and adopting a social mission could make the difference.

“If we don’t do this, we really have nowhere to go,” said Mr. Nelson, referring to the future of academic unions. —Audrey Williams June