OBJECTIVES Interventions promoting habitual fruit consumption have the potential to bring about long-term behaviour change. Assessing the effectiveness of such interventions requires adequate habit and behaviour measures. Habits are based on learned context-behaviour associations, so measures that incorporate context should be more sensitive to expected habit and behaviour changes than context-free measures. This study compared context-specific and context-free measures of fruit consumption habit and behaviour following a 3-week habit formation intervention. DESIGN Prospective online study (n = 58). METHODS Behaviour frequency was assessed across five timepoints, retrospectively (Time 1 [T1], T5) or via daily diary data (uploaded weekly at T2, T3 and T4). Habit strength was assessed before (T1) and immediately after the intervention (T4), and again 2 weeks later (T5). Analyses of variance were run, with time and context specificity as within-subject factors, and habit and behaviour frequency as dependent measures. RESULTS An interaction between time and context specificity was found in both analyses (habit: F(2,114) = 12.848, p < .001, part.η2 = .184; behaviour: F(2,114) = 6.714, p = .002, part.η2 = .105). Expected habit formation patterns 5 weeks post-baseline were only detected by the context-specific habit measure. Likewise, increased behaviour frequency was only found when the target context was specified (p's < .001). CONCLUSIONS Assessments of purposeful dietary habit and behaviour change attempts should incorporate context-specific measurement.