Project‑based organizations have received increasing attention in recent years as an emerging organizational form to integrate diverse and specialized intellectual resources and expertise. A typical problem of these structures is the difficulty in sharing knowledge in and across projects. Besides, project teams are temporary and therefore much learning may be lost when they disband. Very often the storage of lessons learned is not effective; the databases are not widely used and the people are too engaged in their projects to share knowledge or help other people cope with similar problems. The inherent contradiction between organizing for meeting short‑term, project task objectives, and the longer‑term developmental nature of organizational learning processes asks for innovative organizational solutions. How can a project‑based organization be simultaneously oriented to project‑outputs and learning? The processes of knowledge capture, transfer and learning in project settings rely heavily upon social patterns and processes. This situation emphasizes the value of considering a community‑based approach to managing knowledge. Several authors suggest adding a new "dimension" (a "home" for learning, integration and development of specializedtechnical competencies) following a "Crossing‑approach" that leads to design organizational solutions in which project teams (focused on their strengths: outputs, processes or market segments) and learning groups, like CoPs, coexist. The aim of the paper is to investigate the critical points in designing and implementing these innovative organizational solutions (e.g. group design, reward system, participation modes, support mechanisms, formalization degree) that are difficult to manage and little investigated in the literature. We conducted an in depth case study research of an Italian IT Consulting firm: VP Tech. This analyzed firm introduced a particular kind of CoPs called "Practice Groups" (PGs) in a typical project‑based organizational structure. The Practices are knowledge domains (expertises) transversal to the projects or market areas. VP senior executives chose the main strategic practices to be developed and decided to aggregate the main internal experts (PGs) around these knowledge domains. The goals of PGs are to strengthen and diffuse the knowledge developed during previous projects, to monitor the state of the art, and to support professional training and problem solving for people involved in the projects. In VP Tech, PGs represent a: network in which specifically useful information can be found; learning locus in which professional competencies can be improved; social network in which both knowledge exploitation and exploration take place. The conducted case study shows: the different phases and "crisis" in implementing this organizational solution; the specific and innovative mix between formal and informal organizational levers adopted; the circular and virtuous relation between projects and practices.