This descriptive study employed mixed methods to explore preservice teachers' initial knowledge and subsequent use of explicitly taught reading comprehension strategies in primary grade classrooms during a year-long, field-based teacher preparation program. Self-Knowledge Rating Surveys, Strategy Multiple-Choice Tests, strategy logs, lesson plans, self-evaluations, mentor teacher/university liaison evaluations, and interviews with university liaisons comprised data sources. Research questions addressed what reading comprehension strategies primary preservice teachers self-reported they knew; what they demonstrated they actually knew via testing and implementation; and how the self-reports, test results, and implementation compared. Results indicated that neither knowledge nor prior exposure to research-based comprehension strategies transferred into teaching when strong external influences that did not support strategy use such as scripted programs, district policies, high stakes testing environments, and public school mentor teachers' examples of teaching were present.