Background: We examined the influence of text and reader characteristics on sixth graders' inference generation. Methods: Eleven- to 12-year-old US monolingual English speakers (N = 71) and Spanish-English bilinguals (N = 81) read narrative and informational expository texts requiring an inference and answered an inference-tapping question after each text. We examined the influence of language status, word reading ability, knowledge (background knowledge and vocabulary), and reading strategy awareness and use on question accuracy, question-answering times and sentence reading times. Results: Linear mixed effects models predicting response accuracy indicated an advantage for narrative texts, in general, and for participants with higher knowledge. When examining variation across the whole sample, rather than contrasting language groups, faster question-answering and sentence processing times were associated with higher knowledge. Conclusions: Adolescent readers are better able to generate inferences from narrative than informational expository texts, and knowledge has a critical influence on both the process and product of inference generation and may explain reading comprehension performance differences between monolingual and bilingual students.