I thank the Black Hills Institute of Geological Research, Inc., for helping to locate the cranial models used in this study. Kinto and Company granted permission to photograph their models for this paper. C. Herbel also lent skull models for study. I am also grateful to J. Bloch, D. Boyer, J. Farlow, D. Fisher, C. Forster, R. Irmis, G. Knauss, R. Moses, S. Nichols, S. Sampson, and W. Thompson, who patiently listened to my musings on ceratopsid behavior and provided helpful reality checks, and to D. Tanke for his insights into ceratopsid paleopathology. R. Moses assisted with photography. J. Bloch, C. Forster, and J. Mallon critiqued early drafts of this manuscript, and comments by the journal's editors and two anonymous reviewers greatly improved the content of this paper. This material is based upon work supported under a National Science Foundation Graduate Research Fellowship.