Principals' leadership content knowledge in reading was investigated by examining the relationship between the perceived reading knowledge of principals and perceived leadership actions principals take to support reading instruction. Survey results from 78 principals and 1,876 teachers were analyzed. Results showed a positive, statistically significant correlation between principals' perceptions of their reading knowledge and principals' perceptions of the actions they take to support reading. A stronger positive, significant correlation between teachers' perceptions of their principal's reading knowledge and teachers' perceptions of their principal's actions was also demonstrated. These correlations substantiated studies that purported principals with more reading knowledge are more likely to take leadership actions to support effective reading instruction. In this study, reading knowledge was defined by both reading content and pedagogy. Significant but weak relationships were found between: teachers' perceptions of their principal's reading knowledge and type of school; teachers' perceptions of their principal's actions and type of school; and teachers' perceptions of their principal's actions and teachers' years of experience. Non-significant results were found for all other relationships examined. Comparisons of survey responses revealed discrepancies between principals' and teachers' perceptions of the degree of principals' reading knowledge and extent of their actions, which may be important since the literature suggests that differing levels of knowledge and ideas of actions a principal should take can stymie school progress. The study's results suggest: changes in principal preparation programs; ongoing content training for current principals; streamlining principal tasks; and a formal understanding of roles and responsibilities for instructional leadership.