Agents are becoming a popular technology for the development of distributed, heterogeneous and always available systems. The application of agent technologies requires extensions to the existing object-oriented modeling languages to accommodate agent-related abstractions such as roles, organizations and environments. If it is difficult to analyze and establish the wellformedness of a set of diagrams of a UML-like object-oriented modeling language, it gets far more complex when the language is extended to add a set of agency related abstractions. This thesis presents an ontology-based method for structuring and analyzing multiagent systems (MAS) design models. The method proposes the analyses of MAS designs based on a two-phase approach that covers different sets of MAS design properties. These properties are the ones related to each individual diagram and the ones associated with pairs of diagrams. The later take into consideration the interdependencies between diagrams. The method also provides features that allow the suggestion of some design guidelines which may improve the design quality.