A detailed analysis of the occurrence of serious psychological abuse (PSYAB) in one's “worst relationship” was solicited from a nationwide sample of adults in the United States. To designate that they experienced any of the psychologically abusive behaviors, respondents had to have perceived malignant intent by the perpetrator. Respondents reported significant rates of the presence and frequency for 14 specified categories of serious PSYAB as well as for the 42 individual behaviors constituting these categories (i.e., 3 per category). The 3 behaviors within each category frequently co-occurred even though they represented distinct manifestations and increasing levels of severity for that type of PSYAB. Only some of the behaviors demonstrated a relationship between frequency of that behavior in a relationship and subsequent emotional and behavioral impact. Neither demographics nor social desirability were strongly related to report of partner PSYAB.