The relationship between dogs and humans has been represented and contemplated since the beginning of human culture. Lasting expressions of this interest can be found in art, philosophy, literature, and science. With the rise of biological and social sciences in the nineteenth century, disciplinary frames of analysis have increasingly been brought to bear on this topic. These include, among others, evolutionism, biology, genetics, psychology, ethology, anthropology and sociology, with a more recent trend toward interdisciplinary treatments. At present, there is a large body of scientific literature about the relationship between humans and dogs based upon primarily biological, genetic and psychological approaches. It is only within the past decade that sociologists have shown a concerted interest in the social organization of dog-human interaction, and Playing with My Dog Katie is an example of this movement. This unique contribution to the literature - an in-depth case study of a single dog and her guardian (the author) at play uses an ethnomethodological approach, an important aspect of the research is providing the reader with various kinds of data - in written, photographic and video formats - in order to display the phenomenon of play as ordinary, mundane practice. Based upon these data, various theoretical, methodological and empirical issues regarding our understanding of dog-human play are explored. Some of these include: anthropomorphism and anthropomorphic language, the social organization of different 'kinds' (guardian, guide-dog, working dog) of dog-human relationships, the conceptualization of play as an interspecies activity, and intersubjectivity (loosely meaning mutual understanding) between dogs and humans.