This paper describes the design and outcomes of implementing Preffi 1.0, a quality assurance instrument for health promotion (HP) interventions, among Dutch HP professionals. The Preffi instrument promotes a systematic way of working that is driven by evidence, which is expected to lead to high-quality projects and better outcomes. Implementation interventions included nationwide activities aimed at awareness of and positive attitudes toward the instrument, and an intensive 5-day programme for a self-selected sample aimed to enhance self-efficacy and use. Effects of the nationwide activities were measured in two independent representative samples of Dutch HP professionals (N = 120 and 316, respectively), while a cohort design was used to measure the effects of the training programme. The Theory of Planned Behavior was used to guide both the interventions and the study. While the nationwide implementation activities raised awareness of Preffi and contributed to a more positive attitude towards the instrument, a significant increase in its use required a more intensive training programme. Attitude was especially influenced by the perceived value and necessity of a systematic approach, and the usefulness of the instrument. Health managers in The Netherlands failed to stimulate a systematic implementation of Preffi, even though the embeddedness of Preffi in the quality system of a HP team was found to be a major predictor of its implementation. The study showed that determinants of the implementation stages vary by stage.