In this ongoing longitudinal study of adolescent twins/sibling pairs and their parents in Taipei, we aimed to investigate the genetic and environmental influences on adolescent behavioral development, metabolic risk factors, and the associations between the two. Special focus is on anxious depression, metabolic profile, and hormonal factors such as cortisol and leptin. The first wave of assessment was completed during the period of 2002 to 2005 and included 192 twin pairs, 6 triplets, 56 sibling pairs and their first-degree relatives (484 parents and 142 siblings). We are currently in the process of a second wave assessment as follow-up. Dimensional psychological assessments using self-report questionnaires, as well as categorical assessments based on semistructured clinical interviews, were performed. All subjects received a 2-hour oral glucose tolerance test at the examination site. The metabolic phenotypes including body mass index, blood pressure, levels of glucose, insulin, and lipid profile as well as related hormonal levels were measured. Zygosity was determined using DNA, except for a few twins whose DNA was not available. Such a combination of detailed psychological assessments and metabolic function tests is expected to help shed light on the interrelation of psychological well-being and metabolic functioning.