The first section of this monograph shows how, by analyzing the language of personality descriptors, researchers have identified five correlated groups of behaviors. It finds that the most popular formulation of the Five-Factor Model (FFM) is that of Costa and McCrae (1992) and that their nomenclature can be adapted to come up with a version for professional development. These five factors are described: Negative Emotionality, Extraversion, Openness, Agreeableness, and Conscientiousness. Six facets identified for each of these five factors are described. Section 2 presents how the FFM may be used in fostering individual development. It covers guidelines for use of FFM test scores in professional development, including the following: awareness of small interaction effects between all five personality dimensions and aging; the social context of the Big Five; when to use factors and when to use facets; and common themes among the various facets and factors. It also addresses using the FFM in individual coaching and counseling, in a classroom setting, and in personnel selection. Section 3 presents ways in which the Big Five model can be used in working with teams. It looks at how various kinds of relationships--from two-person teams to larger work teams--can benefit from taking time to study the effects of similarities and differences in personality traits among the people in relationships. Contains 21 references. (YLB)