His research focuses on improving access at all levels of the educational process for underserved student groups. Specifically, Hallett studies how mobility influences family dynamics and participation in school. He also directs a college access program for underserved students. William G Tierney is Director of the Pullias Center for Higher Education, University Professor and Wilbur-Kieffer Professor of Higher Education at the Rossier School of Education, University of Southern California. Tierney conducts research pertaining to the effectiveness of programs that prepare low-income youth for college.