Findings from the American Terrorism Study (NIJ grant #1999-IJCX-0005 and DHS/MIPT grant #106-113-2000-064) reveal that unlike traditional criminality, terrorists are much less spontaneous, engage in substantial planning activities, and commit ancillary and preparatory crimes in advance of a terrorist incident. Building on these findings, the goals of the current project were to determine whether (1) sufficient open source data exists to examine the temporal and spatial relationships that exist in terrorist group planning, and (2) if such data do exist, can patterns of routinized preparatory conduct be identified. To accomplish these goals, subject matter experts were selected to identify terrorist groups/incidents that operated or occurred within the United States from four major categories: international; and three types of domestic terrorism -- left-wing, right-wing, and single issue (which was limited to environmental and anti-abortion terrorism). Sixty-seven cases were selected for analysis. Of these sixty seven, sixty of the cases were sufficiently fertile to provide some data for analysis. These included 22 right-wing, 9 left-wing, 10 international, and 17 single issue cases. Information on some 200 terrorist incidents (right-wing, 41; left-wing, 51; international, 58; and single issue, 50) was extracted from open source data on these cases to create a relational database composed of 265 variables. Geospatial data was recorded on some 515 terrorists' residences, planning locations, preparatory activities, and target locations.