Abstract. Complexity in software design refers to the difficulty in understanding and manipulating the set of concepts, models and techniques involved in the design process. Agents are sophisticated software artefacts, associated with a large number of features and therefore Agent-Based System (ABS) engineering methodologies involve considerable design complexity. This paper proposes a framework to evaluate ABS engineering methodologies against a number of criteria related to design complexity. The framework is applied to a number of representative ABS engineering methodologies. The strengths and weaknesses of each methodology with respect to the framework aspects are discussed within the context of a case study involving a virtual enterprise combining manufacturing and logistics services. The evaluation results are used to motivate and guide further work in the area.