This study is based on the premise that research on science textbook content has not specifically dealt with patterned class and grade level differences in how the organization of the content orients students to the cognitive and personality characteristics identified as precursors to scientific careers. The investigation analyzed the effects of social class and grade level on the content of science textbooks from middle- and working-class school districts and from upper and lower grades. Content was examined on the basis of six variables: (1) orientation to cognitive flexibility; (2) orientation to abstract thinking; (3) orientation to communicative fluency; (4) orientation to autonomy; (5) orientation to goal-achieving; and (6) orientation to positive imagery. The results indicated that while more science texts are available to children in middle-class districts than in working-class districts, availability of knowledge important for the development of a scientific role is, on the average, the same for both middle- and working-class districts. In addition, the data suggests that social class has a distinctive effect on orientation to cognitive flexibility. Comparisons are made, with research done on political science textbooks. (TW)