Impulsivity is considered a personality trait affecting behavior in many life domains, from recreational activities to important decision making. When extreme, it is associated with mental health problems, such as substance use disorders, as well as with interpersonal and social difficulties, including juvenile delinquency and criminality. Yet, trait impulsivity may not be a unitary construct. We review commonly used self-report measures of personality trait impulsivity and related constructs (e.g., sensation seeking), plus the opposite pole, control or constraint. A meta-analytic principal-components factor analysis demonstrated that these scales comprise 3 distinct factors, each of which aligns with a broad, higher order personality factor-Neuroticism/Negative Emotionality, Disinhibition versus Constraint/Conscientiousness, and Extraversion/Positive Emotionality/Sensation Seeking. Moreover, Disinhibition versus Constraint/Conscientiousness comprise 2 correlated but distinct subfactors: Disinhibition versus Constraint and Conscientiousness/Will versus Resourcelessness. We also review laboratory tasks that purport to measure a construct similar to trait impulsivity. A meta-analytic principal-components factor analysis demonstrated that these tasks constitute 4 factors (Inattention, Inhibition, Impulsive Decision-Making, and Shifting). Although relations between these 2 measurement models are consistently low to very low, relations between both trait scales and laboratory behavioral tasks and daily-life impulsive behaviors are moderate. That is, both independently predict problematic daily-life impulsive behaviors, such as substance use, gambling, and delinquency; their joint use has incremental predictive power over the use of either type of measure alone and furthers our understanding of these important, problematic behaviors. Future use of confirmatory methods should help to ascertain with greater precision the number of and relations between impulsivity-related components.