In recent year, the role of the pharmacist has evolved from product-focused to patient focused activities. New professional pharmacy services were simultaneously developed and implemented. Implementation, essential to ensure programme delivery and therefore its effectiveness, was seen as a passive process for which diffusion and dissemination were sufficient to translate research into practice. However, the transition from theory to practice is often difficult as different factors hinder or facilitate the implementation of such services. This thesis aimed to understand the gap between theory and practice in identifying factors and key steps for optimal implementation. Three projects were conducted in Belgium and Switzerland; to understand the implementation of an existing programme in Belgium; the isotretinoin pregnancy prevention programme, and to study the implementation of two new developed pharmaceutical services, which include an interview between the pharmacist and the patient and require interprofessional collaboration; the medication adherence program in Switzerland and the medication review in Belgium.