Open Multi-Agent Systems (MAS) are formed by autonomous and heterogeneous agents that may pursue different and even con¿icting goals. Therefore, no assumption can be a priori made about their behaviours. Thus, it is needed to constrain the potential excesses of agent autonomous behaviour by means of regulation of agent interaction. Because of this, `social¿notions, such as organizations, institutions and norms, have been introduced in the MAS research as coordination and cooperation mechanisms. However, there is still a need to de¿ne frameworks which take these organizational abstractions into account. With this aim, this work describes a model of norms for agent organizations that covers both institutional and interaction levels, as well as different types of norms (i.e. constitutive, regulative and procedural norms). This model of norms has been implemented in a speci¿c multi-agent platform, named THOMAS (Methods, Techniques and Tools for Open Multi-Agent Systems), which provides a suitable framework for the management of agent organizations.

(TIN2009-13839-C03-01) project of the Spanish government; Valencian Prometeo project (2008/051); and CONSOLIDER-INGENIO 2010 under grant (CSD2007-00022); FPU grant (AP-2007-01256 awarded to Natalia Criado).