ObjectiveTo analyse text message conversations between peer supporters (called Infant Feeding Helpers – IFHs) and new mothers using qualitative methods to understand how peer support can influence and support women's feeding experiences. DesignQualitative analysis of text messages conversations using both inductive thematic and deductive content approaches to coding. Thematic analysis of the text message transcripts and deductive content analysis was used to code if Behaviour Change Techniques (BCTs) were employed by IFHs in their interactions with women. BCTs coded in text messages were then compared with those tabulated from antenatal meeting recordings and documented in interview transcripts. Participants and setting18 primiparous women and 7 Infant Feeding Helpers from one community site in South-West England. FindingsThree key themes were identified in the18 text message conversations (1679 texts): ‘breastfeeding challenges’, ‘mother-centred conversations’, and ‘emotional and practical support’. The core BCTs of ‘social support’ and ‘changing the social environment’ were found at least once in 17 (94 %) and 18 (100 %) text message conversations respectively. Meanwhile, ‘instruction to perform the behaviour’ was used at least once in over 50 % of conversations. Generally, the use of BCTs was greatest between birth and two weeks during a period of daily texts when women reported many feeding challenges. The number and range of BCTs used in text messages were similar to those documented in audio-recorded meetings and interview accounts. Conclusion and implicationsInfant Feeding Helpers were able to provide engaging and successful breastfeeding peer support through text messages. Messaging was shown to be an appropriate and accessible method of delivering BCTs focussing on ‘social support’ and ‘changing the social environment’. Peer supporters delivering BCTs via text messages is acceptable and appropriate to use if in-person support is limited due to unforeseen circumstances such as the COVID-19 pandemic.