This paper reports on a study to document influences on five beginning mathematics and science teachers' instructional beliefs after a preservice methods course in secondary literacy. The participants were former military officers who had selected teaching as a second career. The study looked at: the teachers' beliefs about uses of literacy in their content instruction from preservice through the second teaching year; influences the teachers perceived as affecting their beliefs; and how and why the teachers' beliefs about literacy in their content instruction changed or remained constant over the 3-year period. Results showed: all five teachers' beliefs had been influenced by the methods course; the teachers' instructional beliefs became more elaborate and specific during their student teaching and first year of teaching; as student teachers, they were influenced by cooperating teachers' beliefs about what "worked" and what "didn't work," beliefs they often adopted unaware of inconsistencies with what they had been taught; all five had concerns about students' behavioral problems; they had to adjust to quick and substantial changes in environment, expectations, and curriculum; and they were influenced by a wide variety of individuals and conditions within and outside of the school. Positive conditions included appropriate curriculum materials, cooperating teachers who favored the strategies, and favorable administrative policies. Negative conditions included lack of time, large numbers of students and/or preparations required, students with many academic or personal problems, and general instability of the beginning teacher's assignments. (Contains 13 references.) (ND)