This study describes the type and extent of intimate partner stalking and threatening behaviors that occurred within 12 months prior to a major assault or attempted or actual partner femicide and specifies which behaviors were associated with an increased risk of potential or actual lethality. The design was a ten-city case-control study of 821 women: 384 abuse victims and 437 attempted or actual femicide informants. Data were derived using a 16-item inventory. Logistic regressions, with adjustments for demographic variables, were used to identify the significant perpetrator behaviors associated with attempted/actual femicide. Women who reported the perpetrator followed or spied on them were more than twice as likely t o become attempted/actual femicide victims. Threats by the perpetrator to harm the children if the woman left or did not return to the relationship place the woman at a ninefold increase in the risk of attempted/actual femicide. Conclusions are that certain stalking and threatening behaviors are strong risk factors for lethality, and women must be so advised.