The Next Generation Science Standards (NGSS) engage students in the epistemic, or knowledge building, components of science through three-dimensional learning. Each scientific domain has its own epistemic aspects that result from different social groups going about science in different ways to conceptualize different bodies of knowledge; education researchers recommend that these be included in science education. While the Science & Engineering Practices and Crosscutting Concepts of the NGSS apply to all sciences, they can be combined in ways that reflect the domain-specific aspects of the life sciences. In this paper, we define and describe simplified epistemic themes, or ways of knowing, within the life sciences for educators to use as a guide when creating lessons and units. Then, we outline example Practice-Crosscutting Concept pairs and groups that curriculum developers can use in learning performance statements to reflect these ways of knowing.