This paper analyses the capacity of youth sport volunteering to contribute to the development of social capital. Following a review of the emergence of social capital as a key theme in UK sport policy, the paper focuses on the ability of a structured sports volunteering programme to equip young people with skills for effective volunteering, and provide opportunities for 'social connectedness' through sports volunteer placements. The study uses survey data (n=160) and qualitative interviews (n=10) with young people to examine how the national Step into Sport programme impacts on participants' personal and skill development, and on their commitment to community involvement. Interviews with education and sport professionals (n=33) provide additional expert perspectives on the programme's impact on participants. Both sets of respondents report strong individual benefits to participants from their involvement, and increased social connectedness in a range of contexts. The paper concludes by considering the implications of the study for claims about the potential contribution of sport to social capital.