Social marketing is the conceptual framework that guided the development of this intervention. Formative (qualitative) research explored the culture of antimicrobial prescribing from both the GP's and the patient's perspective. Through a series of interviews with GPs (n = 15) and focus groups with patients (n = 35), the predictors of a GP's decision to prescribe an antimicrobial and the patient's expectation to receive an antimicrobial were explored.