In 2006, the Mozambican Ministry of Health expanded its existing Indoor Residual Spraying (IRS) programme into Manhiça District in the south of the country. Widespread household coverage is required to have a significant impact on malaria transmission, making acceptability fundamental to success. Between 2006 and 2008 we conducted anthropological research in order to understand acceptability of IRS in the context of the implementation process, policy debates, local and regional politics and historical processes. In the first phase of this qualitative study, conducted between January and April 2006, 73 interviews and 12 focus groups were conducted with key stakeholders from 14 locales in and around the town of Manhiça: householders, community leaders, health care professionals, sprayers, and District officials. Analysis revealed IRS to be broadly acceptable despite very low levels of perceived efficacy and duration of effect. In contrast to previous studies which have linked acceptance to a reduction in mosquitoes, nuisance biting and malaria, we found people's compliance with the programme to be founded on a sense of group-based citizenship. The involvement of local governmental leaders in the intervention appears to have led many to accept spraying as part of their civic duty, as decreed by post-war decentralisation policy in rural areas. We discuss the implications of this 'passive' form of compliance for the acceptability and sustainability of malaria control and other public health programmes.