In Quebec (Canada), the 2004 health system reform brought new challenges for organizations and professionals. To support the reform, the Regional Public Health Directorate of Montreal designed a professional development pilot program, the Health Promotion Laboratory, a strategy to develop and improve health promotion practices and competencies in local health and social services centers. This article reports the results of an analysis of two laboratory sites using a mixed-methods approach and a multiple case study design; the aim was to describe the creation of knowledge through the laboratory and its dissemination in the organization, as well as to identify influencing factors. In-depth semistructured interviews were conducted to collect data on the knowledge creation process and organizational context. Self-administered questionnaires were used four times over the course of each laboratory to measure active participation, commitment, psychological safety, innovation, and satisfaction. Our findings showed that knowledge acquired through participation in the laboratory was disseminated in the host organizations, both through externalization, combination, and, to a lesser extent, internalization. It is highly plausible that team processes and outcomes such as commitment, satisfaction, and innovation influenced this process, as well as contextual factors such as participant turnover, university affiliation, and internal team dynamics. These results show the potential of the laboratory for improving professional practices. They also suggest useful avenues for managers and decision makers interested in implementing such an initiative. Future work should consider the inclusion of other constructs derived from the literature on team effectiveness such as group learning, communication, and skill development.