Self-explaining refers to the generation of inferences about causal connections between objects and events. In science, this may be summarised as making sense of how and why actual or hypothetical phenomena take place. Research findings in educational psychology show that implementing activities that elicit self-explaining improves learning in general and specifically enhances authentic learning in the sciences. Research also suggests that self-explaining influences many aspects of cognition, including acquisition of problem-solving skills and conceptual understanding. Although the evidence that links self-explaining and learning is substantial, most of the research has been conducted in experimental settings. There remains a need for research conducted in the context of real college science learning environments. Working to address that need, the larger project in which this work is embedded studied the following: (a) the effect of different self-explaining tasks on self-explaining behaviour and (b) the effect of engaging in different levels of self-explaining on learning chemistry concepts. The present study used a multi-condition, mixed-method approach to categorise student self-explaining behaviours in response to learning tasks. Students were randomly assigned to conditions that included the following: explaining correct and incorrect answers, explaining agreement with another's answer, and explaining one's own answer for others to use. Textual, individual data was gathered in the classroom ecology of a university, large-enrolment general chemistry course. Findings support an association between the self-explaining tasks and students' self-explaining behaviours. Thoughtful design of learning tasks can effectively elicit engagement in sophisticated self-explaining in natural, large-enrolment college chemistry classroom environments.