Several approaches to assessing the dimensions of the five-factor model are reviewed and evaluated. The items in the assessment instrument may be adjectives or phrases, and the instrument itself may have been developed specifically to measure the five factors or may have been reinterpreted in terms of the five-factor model. Data are presented comparing an adjective-based measure of the model (Goldberg, 1990) with two phrase-based measures (Costa & McCrae, 1985; Hogan, 1986), and recommendations are made for the choice of an instrument in different research contexts. Allport's (1937) distinctions between the structure of the trait lexicon and the structure of personality in individuals are reiterated.