It is often said that so little is currently known about the causes of childhood psychosocial disorders that there is no way to devise appropriate or responsible prevention strategies at the present state of our knowledge. Conduct disorder may be an exception. A careful review of what is known provides a great deal of justification for initiating efforts (as early as infancy) to prevent the occurrence of conduct disorder. Included in this article are data from longitudinal studies that demonstrate the link between early childhood problems and future conduct disorder and a review of the outcome of prevention projects that have been conducted to date. Implications for future work in developing preventive intervention programs for high-risk infants are discussed throughout the article.