Globally, more than 600 million school-age children are at risk of infection with soil-transmitted helminths (STH) and require treatment [1]. These infected children frequently carry the largest burden of disease in a community and are at greater risk of malnutrition and anaemia [2–5], with detrimental effects on educational access and learning as well as mental and physical performance [4,6–10]. Many of these detrimental effects of helminth infection, however, are reversible with antihelminthic drugs [9–11]; thus, the World Health Organization (WHO) advocates reaching a minimum target of regular administration of antihelminthics to at least 75%, and up to 100%, of school-age children at risk of morbidity from STH infection by 2020 [1,12]. The high levels of safety and efficacy of antihelminthic tablets make them ideal for mass drug administration (MDA), and recommended control efforts consist of antihelminthic treatment, administered through MDA, once a year for school-age children in whom STH infection prevalence is between 20% and 49% and twice a year for all school-age children in whom prevalence is at least 50% [13]. By providing easy access to large numbers of children in a structured setting, the school-based deworming model has been successfully used to administer these antihelminthics in multiple settings [14–16]. Thus, school-based deworming, in which the point of care for children is the school and the teachers are administers of the drugs, with critical oversight by health care staff, is recommended in order to cost-effectively and efficiently reach large numbers of children [14–17]. Despite the availability of cheap and efficacious drugs, WHO goals of reaching 75% of at-risk children by 2020 is not on target [18]. Clearly, in order to achieve WHO goals of reaching 75% by 2020, an effort needs to be taken to increase the scale and coverage of deworming programmes to regional and national levels. Box 1 highlights the key elements of a deworming programme implemented in Bihar, which presents a scalable and sustainable school-based model, using the tools available and harnessing existing structures to create a successful, structured deworming programme. Box 1. Key Elements for Success of the Deworming Programme in Bihar Institutional Framework ◆ Ownership of the programme by the government led to increased programme sustainability and continued financial and governmental support. ◆ Additionally, the existence of a multi-sectoral coordination committee (the State School Health Coordination Committee [SSHCC]) provided the necessary supervision, flexibility, and direction to address challenges arising during the programme while ensuring the sustained high profile of the programme. Evidence-Based Design and Implementation ◆ The catalytic role of development partners helped build a strong, evidence-based programme and resulted in overall reduced costs as well as additional high-level government support. Collaboration, Communication, and Coordination ◆ Throughout the design and implementation of the programme, close communication and collaboration among different state government bodies, in particular the health and education sectors, enabled the leveraging of their respective physical infrastructures and human resources and maximized coverage while reducing the overall cost of the programme. ◆ High levels of acceptability of the deworming programme by the community was a result of context-relevant community awareness campaigns that built local ownership of the programme, prevented a purely “top-down” approach to the programme, and increased participation on the deworming day. India is estimated to account for more than a quarter of all children requiring treatment for STH globally [1,19], and in 2009 the State Government of Bihar, in the eastern region of India, planned to initiate a state-wide, evidence-based deworming programme run out of state-schools and with technical support from Deworm the World (DtW). From inception, DtW was technically and administratively supported by Partnership for Child Development (PCD) and Innovations for Poverty Action (IPA) and led by PCD’s Executive Director Dr Lesley Drake, who was seconded to DtW to lead the campaign. This joint initiative is reflected in this paper with the term DtW/PCD. Bihar is one of India’s poorest states, with 8.5% of India’s population and only 1.6% of its gross domestic product (GDP) [20]. The population of Bihar was estimated to be over 104 million in the 2011 census [21] with approximately 28% between 6–14 years of age [21]. Surveys conducted in 2010–2011 found a high prevalence of STH throughout Bihar state [22], and subsequent predictive mapping indicated that at least annual, and in some cases biannual, MDA treatment would be required [17]. This paper outlines the political environment, development, and implementation of all stages of this pioneering and sustainable large-scale deworming programme, which led to the treatment of over 17 million school-age children in Bihar state. In addition, the synergistic support provided by all partners ensured a rapid rollout of the programme, which went from conception to implementation to treatment in less than 12 months, and deworming was rolled out across the state over three months.