Based on a 1967 survey of Mexican American high school sophomores conducted in the "border region" of South Texas, this 1973 follow-up study examined the extent to which: (1) historical changes had occurred in the use of Spanish and English by Mexican American boys and girls over the 6-year study period, and (2) the variations in 1973 language usage patterns by sex and situational context were similar or different for oral speech, writing, and reading. The historical changes were examined in reference to (1) oral speech with parents in the home, with neighborhood friends, and with school friends outside of class; and (2) language utilized for mass media such as radio, newspaper, and magazines. In 1967, interviews were conducted in 7 schools located in the counties of Dimmit, Maverick, Starr, and Zapata. In 1973, 2 of the schools were deleted from the 1967 data set due to lack of cooperation. Both years identical questionnaires were given to all high school sophomores (341 in 1967 and 379 in 1973) present on the day of the study. The 1973 questionnaire contained an extended section on language, reading, and writing patterns. Some findings were: females read more magazines and newspapers in Spanish than males; and in 1973, boys indicated use of Spanish more frequently in all settings than girls, and for both, the frequency of Spanish used decreased from the home setting to the neighborhood, and then to the school setting. (NQ)