The study found that in each dyad examined (e.g., finance-romance, residence-finance, and romance-residence), the fit of the model significantly deteriorated when the coupling between domains was removed. Thus, the statistical model fit the data less well when the correlation (coupling) between the domains was removed. This indicates that the relation unit between domains is critical to understanding development within domains, a central principle of dynamic systems theory. Participants were 200 adults (52 percent women, 48 percent men, 92.5 percent Caucasian, 7.0 percent African-American, and .5 percent Native-American) who ranged in age from 27 to 30 years old. They completed detailed narrative interviews that involved their transition from adolescence (17th birthday) to adulthood (27th birthday) regarding a wide range of developmental domains. The narrative interviews were conducted by telephone between 1997 and 2000. Participants were members of a larger cohort of 821 young adults who had been studied since childhood, when they were randomly selected on the basis of residence in 1 of 2 upstate counties. 6 figures, 4 tables, and 20 references