Book excerpt: The Directorate of Science and Technology (DST) is the primary organization for R&D in the Dept. of Homeland Security. With an budget of $932.6 million in FY 2009, it conducts R&D in several labs. of its own and funds R&D conducted by other gov¿t. agencies, the Dept. of Energy nat. labs., industry, and univ. The directorate consists of six divisions: Chemical and Biological; Explosives; Command, Control, and Interoperability; Borders and Maritime Security; Infrastructure and Geophysical; and Human Factors. Additional offices have responsibilities, such as lab. facilities and univ. programs, that cut across the divisions. In the past, there has been criticism of the DST¿s performance. Although management changes have somewhat muted this criticism in recent years, fundamental issues remain, which this paper discusses. Charts and tables.