This study is designed to compare "traditional" and "immersion" methods of language instruction to determine whether the latter is a viable alternative in four-year, secondary-school language programs. Both methods are evaluated on the basis of student achievement in comprehension, speaking, reading, and writing skills in Spanish. The hypothesis tested--that the experimental group in Spanish immersion would achieve better in second language acquisition--is supported by all objective and subjective data. The report includes an introduction, objectives, procedure, results, conclusions, recommendations, and a bibliography. Tables of statistical data on student achievement are included. (RL)