Background The Hip & Knee Book: Helping you cope with osteoarthritis was developed to change disadvantageous beliefs and encourage physical activity in people with hip or knee osteoarthritis. Aim To assess the feasibility of conducting a definitive randomised controlled trial (RCT) of this evidence-based booklet in people with hip or knee osteoarthritis. Design Phase II feasibility randomised controlled trial (RCT). Method Computerised searches of patients' record databases identified people with osteoarthritis of the hip or knee, who were invited to participate in the RCT comparing the new booklet with a control booklet. Outcomes were measured at baseline, 1 month, and 3 months, and included: beliefs about hip and knee pain, exercise, and fear avoidance; level of physical activity; and health service use. Results The trial methods were feasible in terms of recruitment, randomisation, and follow-up, but most participants recruited had longstanding established symptoms. After one and 3 months, there was a small relative improvement in illness, exercise, and fear-avoidance beliefs and physical activity level in The Hip & Knee Book group (n = 59) compared with the control group (n = 60), which provides some proof of principle for using these outcomes in future trials. Conclusion This feasibility study provided proof of principle for testing The Hip & Knee Book in a larger definitive RCT.