Dog behavior refers to the collection of behaviors by the domestic dog, Canis lupus familiaris, and is believed to be influenced by genetic, social, situational and environmental causes. The domestic dog is a subspecies of the grey wolf, and shares many of its behavioral characteristics.

Although there are important and distinct differences between dogs and wolves, contemporary views of dog behavior are heavily influenced by research on wild wolves.

The social unit of dogs is the pack. From research on wolf packs that are formed in captivity, the pack has traditionally been thought of as a tightly knit group composed of individuals that have earned a ranking in a linear hierarchy, and within which there is intense loyalty. It is believed that dogs were able to be domesticated by and succeed in contact with human society because of their social nature. According to this traditional belief, dogs generalize their social instincts to include humans, in essence "joining the pack" of their owner/handler.

Cesar Millan, (born César Millán Favela; August 27, 1969) is a Mexican-born American dog trainer. A self-taught expert, he is widely known for his television series The Dog Whisperer with Cesar Millan, now in its eighth season and broadcast in more than eighty countries worldwide. Prior to The Dog Whisperer series, Millan focused on rehabilitating especially aggressive dogs and founded the Dog Psychology Center in South Los Angeles (2002–2008) — under construction in a new Los Angeles location as of late 2009.

Millan's first three books, including Cesar's Way, all became New York Times best sellers, have cumulatively sold two million copies in the United States, and are available in 14 other countries. In 2009, in conjunction with IMG, Millan introduced a monthly magazine also titled Cesar's Way — with The Wall Street Journal reporting at that time that half of American consumers recognized Millan. With Ilusión Millan, his former wife, he founded the Cesar and Ilusión Millan Foundation — since renamed the Millan Foundation. He is working with Yale University to create a children's curriculum based on his work.