This manual presents information about major causes of developmental disabilities, discusses strategies to prevent development disabilities, and identifies relevant resources and reference material. Introductory information defines developmental disabilities and prevention (under Virginia statutes). The first section considers causes prior to and during pregnancy, including genetic disorders, infectious diseases, other maternal conditions, nutrition, tobacco, alcohol, drugs, caffeine, environmental exposures, maternal age, and preterm labor. The second section looks at causes during infancy, childhood, and adolescence. These include metabolic disorders, infectious diseases, nutrition, alcohol and drug use, environmental exposures, unintentional injuries, and child abuse and neglect. The third section considers the development of prevention programs and projects, with guidelines addressing needs assessment, planning, evaluation, and critical data elements. The next section presents 43 tables of Virginia statistical data useful in evaluating prevention efforts. The last section presents summary information on 33 Virginia programs which focus on prevention either prior to and during pregnancy or infancy, childhood, and adolescence. References and recommended resources are listed for most sections. (DB)