This research examines adolescents' learning about a historical issue from multiple information sources. Adolescents read 2 contradictory texts explaining the Fall of Rome and thought out loud after each sentence. After reading, a series of questions probed their understanding and ability to reason with the information. Think-aloud protocols were coded for the type of processing they reflected, as well as the content that was utilized (e.g., prior knowledge, other text information). Paraphrases and elaborations were the most common types of processing activity. Elaborations involved connections to prior knowledge as well as other text information (both within and across texts) and often-represented self-explanations. The complexity of reasoning about the historical event was predicted by think-aloud comments that increased the coherence of the texts: self-explanations that used prior knowledge or previously processed text information as well as surface text connections. Results are discussed in terms of theories of text processing from single and multiple texts, adolescents' competencies when processing them, and implications of the research for providing students with opportunities to learn to think in discipline-based ways.