A total of 305 female undergraduates, all of whom had experienced the dissolution of a heterosexual romantic relationship, completed a 48-item questionnaire. The questionnaire was divided into several sections that were designed to obtain information about the participant's experiences following the breakup of a romantic relationship, the demographic characteristics of the participant and her former partner, and other details concerning the background of the former partner. For participants to be included in the "stalked" group, they had to fulfill all of the following criteria: unwanted attention from their previous partner that lasted for at least 1 month, at least 10 separate instances of manifestations of unwanted attention, and the unwanted attention had to induce fear in the participant. Participants who experienced unwanted attention, but whose experiences failed to meet all of the other criteria were placed into the harassed group. Those participants who did not experience any unwanted attention were placed in the no-harassment group. A total of 105 (34.4 percent) participants were classified as stalking victims; 98 (32.1 percent) experienced harassment; and 102 (33.4 percent) experienced no harassment. No differences were found between the three groups in demographic characteristics of participants or former partners. Former partners who were classified as stalkers were most likely to have a history of substance use (alcohol and/or drugs); criminal involvement; violence; mental health problems; difficulties in forming relationships; reacting with inappropriate emotion; and jealousy and suspiciousness of the participant's relationships with others. These findings are consistent with explanations of stalking behavior that emphasize the etiological importance of attachment difficulties. 3 tables and 53 references