While it is well-known that antisocial behavior runs in families, surprisingly little is known about the specific mechanisms by which it is transmitted from one generation to the next. While the intergenerational transmission paradigm is becoming increasingly influential in addressing this issue, very few such studies are prospective, include both parents, focus on early mechanisms, and address female as well as male antisocial behavior. Importantly, none to date have examined biological influences on transgenerational continuity and change, or how they interact with social factors in modulating the transmission of antisocial behavior. The proposed three-generation study attempts to address these gaps in knowledge by capitalizing on a novel design in which I ,795 males and females were tested on psychophysiological, behavioral, nutritional, and cognitive measures at age 3, while their first-generation parents were assessed on psychosocial influences. These second-generation three-year-olds are now aged 30 years and will be retested, together with their third-generation three-year-old offspring, on psychophysiological, psychosocial, cognitive, behavioral, parenting, and antisocial behavior measures. Both the second generation parent and their previously untested spouse will be tested on psychophysiological measures, together with measures of life stress, daily hassles, family conflict, mental illness, and criminal behavior. The study will also assess whether a nutritional, exercise, and educational enrichment from ages 3-5 years in 100 of the second generation subjects, which has lead to increased physiological arousal and attention at age 11 years and reduced conduct disorder at age 17 years, disrupts the intergenerational transmission of antisocial behavior from the second to third generations. It is thought that the study offers a truly unique opportunity to understand the unexplored issue of how biological influences interact with social contexts in either blocking or facilitating the intergenerational transmission of antisocial and aggressive behavior. This new knowledge, if further developed, could contribute to a new generation of more effective prevention programs for reducing antisocial and violent behavior.