One of the most common reasons for relinquishment and euthanasia for otherwise healthy pets is behaviour which owners, or society, regard as problematic. Veterinary nurses are uniquely placed to make an impact on these distressing statistics as clients frequently feel more at ease with nursing staff, who they often perceive as being less intimidating than veterinary surgeons, and as being particulary interested in the general management of their animals. In addition, veterinary nurse-led clinics provide an ideal scenario in which to discuss the way a dog or cat actually copes with its environment, interacts with its owner or family group, and behaves towards unfamiliar individuals, human or animal, both inside and outside the home. This chapter advises on Common behavioural problems; Preventive measures; and Approach to behavioural problems.