This case study investigated a behavioural intervention to reduce caffeine consumption in a 50-year-old female with a 35-year history of consuming >350 mg caffeine per day. The participant completed a behaviour diary for 10-weeks, recording amount of caffeine consumed, type of caffeinated drink, time, location, who she was with and the activity in which she was engaged. She also completed a 10-point performance scale, and recorded tiredness and headaches. Baseline data was recorded for one week, and then Functional Behavioural Analysis of the diary data was used to design an intervention. A graduated intervention was implemented: Stage 1 (1-week), caffeine<=160 mg/day; Stage 2 (1-week), caffeine<=80 mg/day; Stage 3 (7-weeks), caffeine<=35 mg/day. Caffeine was reduced to planned levels during the intervention period. Perceived performance ratings were significantly improved during the three stages of the intervention relative to baseline (p<0.05). Frequency of daily tiredness increased during Stage 2 and decreased overall during Stage 3 relative to baseline. Headaches were at least as frequent during the intervention as they were during baseline. Findings suggest that the intervention was successful over this 2-month period. Further monitoring is recommended in order to ascertain whether headaches and tiredness (possibly symptoms of caffeine withdrawal) persist.