Reading comprehension is a crucial skill that elementary school students must develop in order to learn science. However, there is not yet enough research about the role that multimodal texts play in scaffolding student reading comprehension of complex scientific processes, such as energy transfer. This study explored how verbal and visual resources (scaffolding level) and individual differences (reading skills) contribute to science reading comprehension. One-hundred and sixty Chilean fifth-graders were assessed on reading skills, vocabulary, and prior science knowledge. A counterbalanced design was used to test two groups: Group 1 reads a text with low multimodal scaffolding and Group 2 reads a text with high multimodal scaffolding. Level of text scaffolding was determined by (1) image function, (2) visual-verbal relations, (3) presence of an explicit explanatory structure, and (4) lexico-grammatical resources. General monomodal and multimodal science reading comprehension were assessed with multiple-choice tests. An ANCOVA analysis revealed non-significant differences between groups after controlling for prior knowledge, fluency, and vocabulary. Likewise, a two-factor ANCOVA analysis showed that the high-multimodal scaffolding text significantly boosted science reading comprehension for low-skilled comprehenders. The paper discusses the implications of these findings for pedagogy and research, aiming to foster multimodal literacy for learning in content areas.