The ability to make precise distinctions among related personality constructs helps clarify theory and increases the utility of clinical assessment. In three studies, the authors evaluated the validity of distinctions among four impulsivity-like traits: sensation seeking, lack of planning, lack of persistence, and urgency (acting rashly when distressed). Factor analyses indicated that lack of planning and lack of persistence are two distinct facets of one broader trait, whereas urgency and sensation seeking are both very modestly related to each other and to the planning/persistence measures. The authors developed interview assessments of each, and multitrait, multimethod matrix results indicated clear convergent and discriminant validity among the constructs. The distinctions among them were useful: The traits accounted for different aspects of risky behaviors. Sensation seeking appeared to relate to the frequency of engaging in risky behaviors, and urgency appeared to relate to problem levels of involvement in those behaviors.