Finding a long-term characteristic common to people who develop major depression could clarify who is at risk and how the illness arises. Two investigations focused on serotonin transport and on depressive personality disorder. Bhagwagar et al. (p. 1858) used positron emission tomography with a recently developed, more selective radioactive tracer to measure the protein regulating serotonin transport in the brain. The availability of the serotonin transporter protein in eight brain regions was similar in 24 healthy men and 20 medication-free men recovered from major depression, suggesting that it returns to normal after recovery. Ørstavik et al. (CME, p. 1866) investigated possible overlap between major depression and depressive personality disorder, which is characterized by pervasive depressive thoughts and behaviors. Of 2,801 twins from monozygotic and dizygotic pairs, 14% had a lifetime history of major depression and 2% met criteria for depressive personality disorder. Major depression was common among those with depressive personality disorder, but not vice versa. Although they shared a substantial proportion of genetic and environmental risk factors, major depression was influenced by additional genetic factors.