Paranthropus boisei is a hominin taxon with a distinctive cranial and dental morphology. Its hypodigm has been recovered from sites with good stratigraphic and chronological control, and for some morphological regions, such as the mandible and the mandibular dentition, the samples are not only relatively well dated, but they are, by paleontological standards, reasonably-sized. This means that researchers can trace the evolution of metric and nonmetric variables across hundreds of thousands of years. This paper is a detailed1 review of half a century's worth of fossil evidence and analysis of P. boisei and traces how both its evolutionary history and our understanding of its evolutionary history have evolved during the past 50 years. Yrbk Phys Anthropol 50:106–132, 2007. © 2007 Wiley-Liss, Inc.