Abstract. Grid architectures are execution environments that are known to be at the same time distributed, parallel, heterogeneous and dynamic. While current tools focus solutions for hiding distribution, parallelism and heterogeneity, this approach does not fit well their dynamic aspect. Indeed, if applications are able to adapt themselves to environmental changes, they can benefit from it to achieve better performance. This article presents Afpac, a tool for designing self-adaptable parallel components that can be assembled to build applications for Grid. This model includes the definition of a consistency criterion for the dynamic adaptation of SPMD components. We propose a solution to implement this criterion. It has been evalued using both synthetic and real codes to exhibit the behavior of several proposed strategies. Key words. dynamic adaptation, consistency, parallel computing