The Rottweiler is notably a steady dog with a self-assured nature, but early socialisation and exposure to as many new people, animals, and situations as possible are very important in developing these qualities. The Rottweiler also has a natural tendency to assert dominance if not properly trained. Rottweilers' large size and strength make this an important point to consider: An untrained, poorly trained, or abused Rottweiler can learn to be extremely aggressive and destructive and, if allowed to run at large, may pose a significant physical threat to humans or other animals. They can be strong-willed (bull-headed) and should be trained in a firm, fair, and consistent manner - the owner must be perceived as the leader. If the owner fails to achieve this status the Rottweiler will readily take on the role. However, Rottweilers respond readily to a clear and benevolent leader. Aggression in Rottweilers is associated with poor breeding, poor handling, lack of socialisation, natural guarding tendencies, and abuse.

The Rottweiler is not usually a barker. Male dogs are silent watchers who notice everything and are often quite stoic. Females may become problem barkers in order to protect their den. An attentive owner is usually able to recognise when a Rottweiler perceives a threat. Barking is usually a sign of annoyance with external factors (car alarms or other disturbances) rather than a response to actual threats.