Abstract. \Grande" applications are those with demanding CPU and I/O requirements. They originate in many disciplines, such as astrophysics, materials science, weather prediction nancial modeling, and data mining. Java has many features of interest to developers of such applications. At the same time, there are currently many barriers to the e ective use of Java i n t h i s w ay. The Java Grande Forum is a group of researchers and software developers from industry, academia, and government w i t h a n i n terest in the use of the Java programming language and environment for grande applications. The Forum seeks to increase awareness of issues important to this community, and to work towards their solution. In this article we describe the workings of the Java Grande Forum and the major issues that it has brought to the forefront. We o u tline approaches to the solutions of these problems, and describe e orts to standardize them within the larger Java community. Among the issues addressed are: oating-point performance, multidimensional arrays, complex arithmetic, fast object serializations, and high-speed remote method invocation (RMI).