This article offers a way of viewing mathematics as social, drawing upon research on numeracy practices at home and at school carried out by the School and Community numeracies team in the Leverhulme Numeracy Research Programme, a five-year research programme (1997-2002) at King's College London. Within the school and community focus of the Leverhuhne Programme, the authors sought explanations for and understandings of the correlation between social factors such as relative poverty and family background and educational attainment as well as outcomes of school numeracy. The research was therefore founded on a model of what the social means when looking at mathematics. This article seeks to explain this use of "social" and draws on this research as an illustration of these ideas. Fieldwork within the research was ethnographic in style (Green and Bloome, 1997). It was conducted in three schools, Mountford (located in an economically disadvantaged area in a town on the south coast of England), Rowan (located in a wealthy London suburb), and Tarnside (located in multicultural and multilingual inner London). The article begins with a brief excerpt, that the authors call a "numeracy event"--those "occasions in which a numeracy activity is integral to the nature of the participants' interactions and their interpretative processes" (Baker, 1996)--from the field diaries of Alison Tomlin. They then provide preliminary interpretations of the excerpt as well as two implications for schooling. This is followed by a discussion of the broader issues: cultural issues, relationships between schools and homes, and contrasts between home and school numeracy practices. The hope is that the approaches used in the project and the concept of numeracy practices indicated in the article will make a contribution towards ways of researching and understanding the relationship of home and school numeracy practices that allow bridge-building to occur.