Global software market is more demanding. Model driven development (MDD), which builds software from models and not from code, promises quality and productivity improvement. A software process model supporting the MDD paradigm would hopefully facilitate the adoption of MDD. This paper proposes a software process improvement model oriented to small organizations, including goals and best practices, based on standards, and complemented by specific elements for MDD. The model also includes an assessment method aimed to determine the current state of the organization and to indicate improvement plans to gradually evolve across the model. Model and method are being applied in or order to evaluate its benefits.