INTRODUCTION

This issue of Seminars in Speech and Language is a tribute to Professor Mark Ylvisaker, who passed away in May 2009. This issue recognizes the enduring nature of the extraordinary contributions Professor Ylvisaker has made to traumatic brain injury rehabilitation around the globe. Contributors to this special issue were invited to describe how Professor Ylvisaker influenced their work, and the resulting compilation demonstrates the breadth of his intellectual and clinical advances. In selecting the authors for this issue, I found myself writing down a list of people who are both friends and colleagues from all corners of the globe. Mark had a propensity for travel and took every available opportunity to visit new countries and present his ideas to clinicians and researchers. Mark consulted to rehabilitation and education programs in 13 countries on five continents. As a result, the contributions in this issue are drawn from Australia, where he had many visits and was much loved (Skye McDonald, Jacinta Douglas, Leanne Togher); New Zealand (Brigitte Larkins); South Africa (Glenn Goldblum); and, of course, his home, the United States (Tim Feeney, Lyn Turkstra). Each contributor in this special issue has spent considerable time with Mark, both professionally and personally. Mark had a wonderful ability to stay in touch with us all and to make sure we stayed in touch with each other. He would enjoy the fact that he has brought us all together again in this issue.