How do children and pets build daily relationships that contribute to either challenging or reproducing dominant classificatory categories and established boundaries between human and non-human worlds? This project aims at exploring this question, drawing on some facts that have stimulated scientific curiosity around the topic:the contrast between normative changes related to animal rights/protection and the massive numbers of errant and institutionalized dogs and cats, due to different forms of abuse and neglect; the dramatic drop of fertility rates, with children becoming rarer in number, along with their growing centrality in the family and parental investment in their education; homes that become 'technological playgrounds' where children learn and play, and a pet becomes an option for partisans of an 'experiential pedagogy', perceived as a way to retrieve a relationship with nature and the 'world we have lost'. Furthermore, since modernity, children and animals share time-lagged but similar processes of recognition as subjects of fundamental rights. Informed by a 'theory of practice' framework, and drawing on interdisciplinary literature (on childhood, friendship, affect, and human-animal studies), the project aims at studying the relationships between children and pets. It pays special attention to their affective practices, defined as forms of embodied meaning-making. It is suggested that children and pets co-produce the hybrid worlds they are embedded in, through practices that may either reproduce, or confront, the species barrier. It is hypothesized that, when these relationships are built in the way either of kinship, or of friendship, that barrier is challenged. More specific questions are: what are the dimensions (educational, instrumental, ludic) involved in practices between children and pets? How do these practices impact both on the child and the pet, namely to the development of mutual empathy? How do they contribute to drawing the boundaries of what is an 'animal', a 'pet', a 'child', or a 'friend'? How do they intertwine with parental education and caring practices, towards both the child and the pet, as well as the overall material arrangements of the household? Methodologically, the project follows a qualitative design. The unit of analysis is the relationship between the child and (the) pet(s) (cats/dogs); children will be given a voice (and heard) and their relationship with pets observed in domestic context. The multi-method approach will comprise both visual and verbal data, collected via ethnography and direct observation, visual and participatory methods, and photo-eliciting interviews. The project develops a sociological perspective that has remained underexplored: the relevance of the child-pet relationship for both sides; and how it is built through affective practices. It is groundbreaking in Portuguese social sciences, and it contributes with an original context specific case study to the international literature.