There is substantial literature documenting the myriad mutually beneficial effects of the human-animal bond. While such relationships typically enhance the health and well-being of both people and their animal companions, the bond can weaken or fail to be established if the animals do not meet the expectations of the people with whom they interact. The behavioral component of animal welfare is particularly important in this regard, and requires significant attention, as owners of companion animals are often intolerant of behavior problems. These include behaviors characterized as nuisances, such as excessive vocalizations, those that result in aggression toward people or other companion animals, or behaviors that result in injury to the animal or damage to property. Problem behaviors are among the most commonly stated reasons for cat and dog relinquishment, abandonment and euthanasia. Thus, understanding key factors that impact behavioral well-being in these species is important whether the animals are maintained in or intended to be rehomed from breeding programs, shelters, rescues or elsewhere. Consequently, a comprehensive assessment plan for meeting the needs of animal companions that includes their mental and behavioral well-being is necessary to protect the human–animal bond. It is therefore imperative to develop and validate key metrics of companion animal welfare that are practical for field as well as laboratory purposes. Considerations and challenges in developing such metrics will be reviewed, using the development of care and welfare standards for breeding dogs for illustrative purposes.