When students learn, they activate, use, revise, and acquire knowledge. As such, knowledge is a fundamental asset. We advocate for an asset-based approach which capitalizes on students' knowledge through prompts and activities that invite learners to leverage what they already know. Considering knowledge as an asset means that educators must consider multiple aspects of knowledge rather than just the amount of knowledge related to a target domain. This article explores how knowledge can be conceptualized across multiple types (e.g., explicit vs. implicit, declarative vs. procedural, metacognitive, epistemological, disciplinary, formal vs. informal) and dimensions (i.e., amount, accuracy, specificity, coherence) and how acknowledging and responding to the multi-faceted nature of knowledge supports learning. Effective learning comes from capitalizing on what a student already knows and engaging the student in active, knowledge building which results in more meaningful and long-term learning. [This chapter was published in: "International Encyclopedia of Education, 4th Edition, Volume 6," Elsevier, 2023, pp. 209-218.]