This paper examines experience with two decades of global model-building efforts, focusing on their impact and on methodological issues. Adopting a developing country perspective, the paper then explores what may be considered as a next stage in their evolution: the development of comprehensive policy-oriented models at the national level. The models developed at GRADE in Lima, Peru are used as an illustration of what can be achieved with national comprehensive models as policy exploration tools. The paper ends with a review of the difficulties and challenges that will be faced in the transition from global to national comprehensive models.