The explanations that participants give themselves (self-explanations) while learning or solving problems have been shown to be positively associated with various performance measures. The major aim of this study was to identify patterns of self-explanation that distinguish between good and poor problem solvers. Thirtytwo Grade 9 students were asked to solve 3 mixture problems-1 warm-up problem and 2 test problems-while thinking aloud. The problem-solving process was videotaped, protocols were transcribed, and 5 content categories were identified. Through a sequential analysis, patterns of self-explanation that differentiate between good and poor problem solvers were identified. THE NOTION THAT THOUGHT is mediated by language has been the sine qua non of sociocultural (Vygotskian) psychology. According to Vygotsky and his followers (Cole, 1996;John-Steiner & Mahn, 1996;Vygotsky, 1978; Wertsch, 199 l), one cannot properly comprehend human thought without considering the symbolic systems that mediate it. In that sense, we think through the symbolic systems the culture provides us, with language as the most important symbolic system.One of the major aims of research in learning and instruction has always been to identify strategies that foster learning and problem-solving performance. In that context, it is important to inquire how certain forms of verbal mediation influence our cognitive functioning. One such avenue of inquiry is the way in which explanations students give themselves (self-explanations) during learning or problem solving mediate their performance. Researchers have shown that selfexplanations during learning or problem solving are positively correlated with learning and problem-solving measures (e.g., Chi, Bassok, Lewis, Reimann, & Glaser, 1989;Neuman & Schwarz, 1998). Although self-explanations may be manifested through nonverbal forms of mediation (e.g., by using a graph or table), most studies of self-explanation have focused on the relation between measures of learning and the generation of verbal self-explanations.Self-explanation is not an isolated event but a dynamic process of using language to mediate thought. That is, explanations are generated as a sequence of utterances, and there is good reason to believe that those utterances are somehow connected. The authors of previous studies of self-explanation have ignored the dynamic process of self-explanation; they have used traditional experimental methodology such as regression analysis or factorial design to investigate the relationship between amount of self-explanation and students' performance on learning tasks. Such traditional approaches to the study of self-explanation can be explained on theoretical and methodological levels. On a theoretical level, most studies of self-explanation were conducted with an experimental perspective that emphasized the effect of intervention rather than the examination of a process. In contrast, the sociocultural perspective points to the possible benefits of inquiring into a phenomenon through a microg...