Background Increasing immunization in the Gypsy, Roma and Traveller (G&T) community is a key priority for improving health outcomes in this community. This study aimed to explore G&T parents: (1) beliefs about childhood immunization; (2) beliefs about the risks of immunization and non‐immunization; (3) perceived obstacles to, and facilitators of, immunization and (4) views on increasing immunization levels. Method A cross‐sectional, qualitative study was conducted comprising of five focus groups with 16 site‐dwelling G&T women with pre‐school aged children. Data were transcribed verbatim and analysed thematically. Results Five main themes were identified: Lay understandings of causation and risk; Timing of immunization; Children being perceived as vulnerable; The fit between lifestyle and healthcare provision; The impact of living with a high burden of disease. Conclusion Understanding of the risks and benefits of measles, mumps and rubella immunization did not differ significantly from the wider population or those promoted by the health service. The majority of barriers stemmed from living with the effects of long‐standing health inequalities, which posed further barriers to accessing immunization, and shaped beliefs about immunization. Factors facilitating uptake occurred where access to immunization services was made flexible, e.g. immunization on traveller sites.