Since 1986, this annual cost study has provided a measure of what it costs the taxpayer each year to support families that began when the mother was a teenager. Three sets of public costs are estimated; these reflect: (1) how much the United States spends as a result of teenage childbearing in a given year; (2) the public cost over a projected 20-year period for a single family that began in 1989 by a teen birth; and (3) the cost of all teen families begun in 1989 over the following 20 years. The study has expanded to include estimates for five states and two cities that are representative of different regions around the country. The states--Vermont, Louisiana, Wisconsin, New Mexico, and Oregon--and the cities--Baltimore and St. Louis--reveal a broad range of costs for the locales they represent. Findings reveal a rise in teen birth rates and a greater than expected increase in the costs of teen pregnancy. The latter finding, ironically, reflects an encouraging development: an expansion of Medicaid coverage for low-income, pregnant women and children under 6 years of age. Introductory background information is followed by sections concerning 1989 estimated costs of teenage childbearing in the United States and in the five states and two cities, the case for teen pregnancy prevention, study methodology, and data sources. (RH)