In both popular media and scientific literature, it is commonly stated that breeds of dogs differ behaviorally in substantial, consistent and predictable ways. Since the mid-twentieth century, scientists have asked whether meaningful behavioral differences exist between breeds of dogs. Today, there are over 1000 identified dog breeds in the world, but to date, fewer than one-quarter of these are represented in studies investigating breed-specific behavioral differences. We review here scientific findings of breed differences in behavior from a wide range of methodologies with respect to both temperament traits and cognitive abilities to determine whether meaningful differences in behavior between breeds have been established. Although there is convincing scientific evidence for reliable differences between breeds and breed groups with respect to some behaviors (e.g., aggression, reactivity), the majority of studies that have measured breed differences in behavior have reported meaningful within-breed differences has well. These trends appear to be related to two main factors: the traits being assessed and the methodology used to assess those traits. In addition, where evidence for breed differences in behavior has been found, there is mixed consistency between empirical findings and the recognized breed standard. We discuss both the strengths and limitations of behavioral research in illuminating differences between dog breeds, highlight directions for future research, and suggest the integration of input from other disciplines to further contribute to our understanding of breed differences in behavior.