The importance of listening to and engaging publics in the design and implementation of immunization policies and programmes has been well established (Waisbord 2004; Cooper et al. 2008; Obregon 2009; Larson et al. 2010; Larson et al. 2011). There are a number of examples of the costs (financial and social) of not involving publics early, the most acute being the boycott of polio vaccination in five states in Northern Nigeria in 2003 (Yahya 2007). Several papers in this special issue highlight potential roles of publics in the introduction of new vaccines, mostly at the level of implementation, but some point to the importance of bringing the role of citizen voices earlier into the decision-making process—i.e. not just as players to implement decisions made by central authorities, but to be a part of decision-making processes (Wonodi et al. 2012). The ‘public’ in public engagement could be a variety of stakeholders; such as individuals, parents, policy-makers (Mantel and Wang 2012), researchers and clinicians (Burchett et al. 2012), immunization programme managers (Brooks and Ba-Nguz 2012; Gordon et al. 2012), ‘global/regional bodies’ (Makinen et al. 2012), advocacy groups, or influential individuals (Makinen et al. 2012), such as religious leaders (Wonodi et al. 2012). The social network analysis around new vaccine introduction in Nigeria recognized that ‘vaccine programmes can benefit from engaging religious leaders in discussions about the needs of their community and how best to meet them’ (Wonodi et al. 2012). The polio boycott in Northern Nigeria in 2003 highlighted the importance of religious leaders in influencing parents, first negatively and then positively towards the polio vaccine. There are several different ways of engaging publics, from town hall meetings and focus groups to hotlines, consultations and social mobilization activities (Wonodi et al. 2012), and engaging with religious leaders. Effective public engagement strategies in the polio eradication effort in India contributed to the success, resulting in no polio transmission in over one year since January 2011 (GPEI 2011). Public engagement is not a communications campaign informing the public when to get their vaccines (which is also needed); it is about dialogue with stakeholders and about trust building (see Box 1). During the introduction of a new vaccine, it is important to engage with the public early on, during the planning stages, in order to anticipate and to identify any potential concerns or issues as well as opportunities. Public engagement should also be carried out throughout the implementation of vaccination programmes to stay alert to any emerging concerns as well as to sustain the support of the public. The ‘public’ are a broad population with a considerable amount of diversity. We need to understand this diversity and to listen to the views and perceptions of the different sections of the public. We also need to engage with the public as advocates and as implementers and to respond to any concerns as they arise. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Published by Oxford University Press in association with The London School of Hygiene and Tropical Medicine The Author 2012; all rights reserved. Health Policy and Planning 2012;27:ii77–ii79 doi:10.1093/heapol/czs038