How science understandings are communicated and how students construct meaning of these communications are central issues in epistemic research. Students' metacognition of the meaning-making process is embedded in this line of research. This paper reports a study to examine children's declarative, procedural, and conditional knowledge of science text and science reading. A random subsample of 52 subjects in grades 4 (n=10), 5 (n=11), 6 (n=11), 7 (n=10), and 8 (n=10) from a sample of 500 students who completed a survey instrument of a larger study was chosen to be interviewed. The gender distribution was 26 males and 26 females and the subjects ranged between high (n=21), average (n=23), and low (n=8) reading ability. Interviews were conducted after students had completed a 63-item survey instrument designed to determine their metacognitive knowledge of science reading and science text. One of five interview protocols was utilized. Each protocol set is based on 1 of the 21 strategic characteristics of an efficient, successful reader of science text. Each protocol involved declarative, procedural, and conditional questions related to that specific characteristic. Student responses were scored by the researchers and analyzed both quantitatively and qualitatively. Analysis provided the basis for a 10-point profile of the composite metacognitive knowledge of science reading and science text of middle school students. Results indicated: (1) no significant grade differences for any strategy or metacognitive domain; (2) significant reading group differences on one strategy and all cognitive domains; (3) significant gender differences favoring females on two strategies and no differences for metacognitive domains; and (4) good readers' metacognitive knowledge was generally higher than poor readers. An appendix lists the questions for specific strategy and metacognitive domains. (Contains 44 references.) (MDH)