Interactions between cetacean species are common events that can lead to the formation of mixed-species groups, which have been reported in both captive and wild odontocetes. However, mixed groups containing Indo-Pacific humpback dolphin (Sousa chinensis) and the finless porpoise (Neophocaena phocaenoides) rarely have been seen, and detailed interactions between these 2 species have been limited. For the first time, this paper describes wild Indo-Pacific humpback dolphins assisting a finless porpoise (N. p. sunameri) calf in Xiamen waters, China. A group of 8 humpback dolphins amicably herded a finless porpoise calf for more than 3 h. The humpback dolphins accompanied the finless porpoise calf and took turns pushing the calf out of the water to breathe. This paper provides a detailed behavioral description of these interactions, and we discuss the potential causes of this event.