Dynamic loading of Java classes at runtime provides tremendous flexibility in the development ofenterprise systems. It provides for the basis of "application servers", and allows even simpler,lighter-weight systems to accomplish some of the same ends. Within Java, dynamic loading is typicallyachieved by calling the forName method on the class java.lang.Class ; however, when Class.forName is naively called from within an Extension, strange errors can occur. This paper describes why those errors occur, and how Java2 provides two facilities, one a modification to theforName syntax, and the other, called the "Thread context ClassLoader", to avoid them. This paper assumes you are passingly familiar with Java Reflection, and have at least a general idea ofwhat Java ClassLoaders are and how they are used within Java code.