Mixed-species associations are temporary associations of individuals of two or more animal species involved in similar activities. Among marine mammals, mixed-species associations are relatively uncommon and appear to vary by such factors as region, season, prey availability, and behavioral state. While mixed-species associations occasionally are reported for marine mammals in portions of the Southern California Bight (SCB), little attention has been given to understanding the broader extent and context of these interactions within the larger SCB. Over a 6-y period, we conducted line-transect aerial surveys throughout much of the SCB and became interested in the mixed-species associations we observed. Herein, we examine the relative frequency of species and behaviors found in marine mammal mixed-species associations, and describe those involving Risso’s dolphins (Grampus griseus) since it was the most common species among mixed-species associations. We review and compare our observations with other data on mixed-species associations of marine mammals from California waters.