Many children would benefit from a diet richer in vegetables and fruit. Reluctance to taste new foods is widely recognised as a barrier to healthy dietary variety in children. ‘Flavour School’ is a programme of ‘sensory food education’, aiming to increase children’s confidence and curiosity in exploring foods and flavours, especially vegetables and fruit. We report a pre-registered, cluster-randomised controlled trial to assess the outcomes of the Flavour School programme, in n=160 children aged 4-7 years from 5 UK schools in London and Leeds. Children either received the Flavour School programme (experimental group n=84) or no intervention (control group n=76), in a two-level design with children clustered within school classes. Data collection consisted of video recorded behavioural observation during a tasting activity designed to resemble a Flavour School activity, conducted before and after the intervention. Linear regression models were used to fit relationships between independent variables and outcomes; Willingness-to-taste, Enjoyment (positive/negative facial expression), and Expressiveness (change in facial expression). Most children engaged readily in the tasting activity at baseline. At follow-up children engaged with the tasting activity even more readily (on average biting one more food sample), with no significant effect of the intervention. We interpret these findings to indicate that intra-individual tasting behavior in children is context-dependent. Our results suggest that the context of sensory food education activities facilitates openness to tasting across the normal range of individual traits. However, we find no evidence that receiving sensory food education makes a reluctant taster into a less reluctant taster; no ‘curative’ effect of the intervention was observed. Rather, even usually fussy/reluctant children were often willing to have a go at tasting in the conducive context of an exploratory activity. Trial registrationISRCTN: 40249947 Date assigned 17/03/2020 Last edited 24/10/2022 Version 1.2 Trial Acronym OASES (Outcomes Assessment of Sensory Education in Schools)