The research used the Chicago definition of gang-related homicides; this definition was more restrictive than that previously used in Los Angeles. Results revealed that a motive-based definition of gang-related homicide yields about half as many gang homicides as does a member-based definition. In addition, the character of motive-defined and member-defined gang homicides are quite similar. The character of the former may be related more to the gang-on-gang nature of the incidents than to motive; certainly a redundancy exists between the two. Moreover, when contrasting gang homicides with nongang homicides, it does not matter much which definitional approach is used for purposes of describing the settings and participants of each. Furthermore, the motive-defined approach allows somewhat more successful classification of gang and nongang cases on the basis of setting and participant characteristics, but not at all in proportion to the information available. Overall, findings indicated that estimates of the prevalence of gang violence can vary widely between cities using different definitions of gang violence. Tables, notes, and 17 references