As evidenced by the popularity of animal behavior shows and books, online viral pet videos, and the presence of dogs or cats in two-thirds of American homes, pets clearly play an important role in many Americans’ lives. At the same time, however, millions of pets are abandoned, abused, and euthanized every year. What should we make of these seemingly conflicting realities? How do Americans really feel about and treat their pets? And what explains the differences? In recent years social scientists have begun to investigate the various and changing interactions between humans and animals. In particular, a growing body of research examines humans’ relationships with pets, most often dogs and cats. This paper reviews recent research in this field. After discussing what differentiates pets from other animals, the paper begins with a review of research investigating the meanings and roles of pets in people’s lives and the nature and benefits of human-pet attachments. Secondly, it reviews research on the factors that help explain why some people have a higher regard for pets than others. The paper concludes with a discussion of some of the limitations of existing research and some suggestions on how to expand future investigations.