AbstractDue to its salient properties, mobile agent technology has received rapidly growing attention over the last few years. Many developments ofmobile agent systems are under way in both academic and industrial environments. MOLE is one of the first mobile agent systems that has been developed in the Java language; the first version came out in 1995. Since then MOLE has been constantly improved, and provides a stable environment for development and usage of mobile agents in the area of distributed applications. Furthermore, it has been used extensively in our research at the University of Stuttgart.In this paper we describe the system MOLE, some of its unique concepts and their implementation, and the results of our research in the areas of security, transactional support, and control mechanisms. Additionally, we discuss some applications built on MOLE. Copyright © 2002 John Wiley & Sons, Ltd.