BACKGROUND: Recent debates on the introduction of new childhood vaccines in the UK have suggested that 'peace of mind' (PoM) might influence decision making. The aim of this study is to ascertain the importance of 'PoM' in individuals' decision making. METHODS: Four focus groups were conducted in the UK. Participants were 22 females and 2 males, aged 18-74 years, with a selection of non-parents, parents, guardians and foster carers. Data were analysed using an inductive thematic framework approach and conceptualised using the Health Belief Model, which provided an overview of participants' perceptions and behaviours about childhood vaccinations. RESULTS: Vaccine associated PoM was associated with individuals' perceptions of disease severity, with individuals feeling more reassurance after obtaining vaccinations against diseases that they considered to be severe compared to relatively mild diseases. Conversely, concerns about vaccination side-effects reduced participants PoM, but the duration of this effect varied between individuals. Other factors, such as social pressure and the emotional anxiety related to children's feelings, or physical reactions, to vaccinations also negatively impacted on participants' vaccine associated PoM. CONCLUSION: Vaccine associated PoM was a consideration for some participants seeking vaccinations but was only a minor motivating factor for these individuals. These differences stemmed from whether participants received PoM from the uptake of a vaccination because they perceived some intrinsic benefit from it or, conversely, they considered vaccinations as a routine health intervention. Overall, vaccine related PoM varied between participants in magnitude and fluctuated over time, even in the same individuals.