The paper first develops the rationale for a definition of "terrorism" that draws the line between types and levels of violence. Fists, bricks through windows, and even cudgels may be used at one level; whereas, bombs and guns are used by the groups that have gained the attention of commentators. Such a definition must be extensive rather than stipulative, because it is necessary to portray a picture of the phenomenon before it can be defined. It must also take into account the fact that a lot of the violence used is under the intention of improving bargaining power or preventing other social groups from increasing their bargaining power. The focus of interest then is the use of particular tactics by pressure groups and embryo parties. As a contribution toward building the definition, this paper develops a typology of groups and the circumstances in which they choose to use a paramilitary form of violence (bombs and guns). It also links the type of group with background circumstances. Nine examples of the use of the suggested typology of groups focuses on "action" and "intention" as bases for classification.