The Advanced Computing for Science (ACS) Department seeks to allow scientists to address complex and large-scale computing and data analysis problems beyond what is possible today. The department is developing software components which will operate in a distributed environment. Research areas include providing tools to facilitate Grid services; building prototype tools to explore models of informal collaboration between geographically remote researchers; techniques for assuring the security of distributed applications and for providing site security while permitting access by a wide variety of remote applications; and developing customized tools and support for specific scientific collaborations.