The ratio technique, requiring only simple arithmetic calculations, uses historical information as a basis for projecting school enrollment. In the author's survey of state education agencies, 84 percent of the respondents indicated that they used a ratio technique. This study reviews four different approaches to use of the ratio method in projecting enrollments, utilizing base periods of five, seven, and ten years as well as a weighted average of ratios from a base period of five years. The four methods were employed in an examination of Tennessee's public school districts. Enrollment forecasts were made for the school years 1974-5 through l978-9. In this paper these forecasts are compared to actual enrollment figures for those years. The computations of the percentage of error for each method and district suggest that forecasts are more accurate for systems with stable or increasing enrollment. Forecasts for systems with declining enrollment were found to be underestimated. No single method was proven to be consistently more accurate than the others under all circumstances. (Author/WD)