The environment in which the automobile travels can be divided into three general elements: (1) roadway geometry, (2) roadside conditions, and (3) other factors. This paper instructs the beginning investigator on how to assess the role of the environmental elements in accident causation and accident severity. Very few tools are needed for a very adequate environmental analysis. Easily identifiable roadway geometric elements associated with highway safety include curvature, grade, roadway and lane width, and sight distance. More subtle elements are pavement crown, superelevation, pavement rutting, and transition curves. Water, snow, ice, or debris on the pavement surface are also influences. Although the clear roadside has been a principal objective of highway engineers, roadsides are still riddled with booby traps for the errant vehicle. The technology is available to make great strides in environmental safety improvements, but hazardous locations have to be brought to the attention of the responsible agencies.