Learning materials incorporating written texts as well as instructional pictures are the basis for learning in many subjects. However, text-picture integration makes high cognitive demands of learners, and it seems plausible that the development of this competence is influenced by teachers' instructional skills. The present studies investigated first the differential role of learning materials integrating text with pictures in geography and biology classes compared to German language arts instruction, and the accuracy of teachers' diagnostic judgments concerning materials and student competencies from teachers who majored in different subjects. Second, we examined whether teachers with different majors systematically differ in their pedagogical beliefs and motivation to use text-picture materials, and if these differences predict both the quantity as well as the quality of instruction using both text and pictures. We present teacher questionnaires and test data from two independent studies, including "N" = 108 teachers with biology/geography or German major with in total over 1,000 students from grades 5 through 8 of all school tracks in study I, and "N" = 107 teachers with their students in study II. Descriptive statistics, "t" tests, and SEM are reported. The results indicate that teachers currently do not sufficiently manage to judge these learning materials, and that for the most part, variation between teachers was not systematically attributable to their subject major. At the same time, the differences observed between teachers in pedagogical beliefs and motivation had important consequences for both the quantity and quality of instruction using both text and pictures. Implications are discussed in regard to further research and educational practice.