Examines the determinants of language choice using sociodemographic, behavioral, and ideological data on a sample of 180 high school students in the city of Valencia, Spain and the neighboring town of Xativa. Evaluates the relative importance of sociodemographic and ideological factors on the choice of Valencian or Castilian in several contexts and looks at geographic origin, social class, political orientation, attitude, and declared social identity of the study informants. (Author/VWL)