Modern personality theories differ in their assumptions about the structure and etiology of the interplay between personality traits and motivational constructs. The present study examined the genetic and environmental sources of the interplay between the Big Five and major life goals concurrently and across time in order to provide a more decisive evaluation of the conflicting assumptions stated in the five-factor theory as opposed to socioanalytic conceptions. Traits and goals were assessed twice across a 5-year period in a sample of 217 identical and 112 fraternal twin pairs from the Bielefeld Longitudinal Study of Adult Twins. About 30% of the variance in agency and communion life goals was genetic; the remaining variance was due to nonshared environmental effects, whereas shared environmental effects were negligible. Both heritable and environmental variance in goals could partly be accounted for by genetic and nonshared environmental effects on personality traits. Across time, we revealed reciprocal genetic and environmental effects between traits and life goals. In sum, our findings yield partial support for both of the 2 competing personality theories, suggesting a readjusted picture of the interplay between traits and goals.