Data from three different teacher surveys are compared in a study of Paraguayan bilingual teacher attitudes on the choice of the language to be used in the classroom. The surveys were conducted in 1976, 1979, and 1986. Paraguay was chosen because of the stability of Guarani-Spanish bilingualism in that country and in its educational system. A secondary analysis was conducted on the survey data. The three surveys are described, and the results are compared and contrasted. These aspects of teacher attitudes are examined: (1) teacher characteristics and preparation; (2) instructional techniques; (3) teacher home language use; (4) teaching experience; (5) language use during recess and in meetings; (6) Guarani use in class during the course of the school year; (7) reasons for using Guarani; (8) attitudes toward Guarani as a subject matter; (9) attitudes toward Guarani as an informal language; (10) and the impact of Guarani use in teaching and on achievement. Results suggest growing positive attitudes about the instrumental use of Guarani, particularly orally, but show continued high esteem and preference for Spanish. Ambiguities reflect mixed teacher awareness of language use and choice. Issues in the methodology of survey comparisons are discussed, and potential areas for further research are suggested. (MSE)