Educators are increasingly applying problem-solving through instructional strategies, such as inquiry-based learning. An important aspect of problem-solving includes the decision-making process and the rationale for learners' choices. Although prior theories and models indeed yield important insight in other areas of problemsolving (e.g. -scaffolding, argumentation, reflection), the decision-making process has only been implicitly referenced within learning design. To better understand the role of decision-making and apply it towards design, the article reviews the theoretical basis of the following overarching frameworks: normative, descriptive, prescriptive, and case-based decision-making theory (CBDT). For each approach, an example is included that instantiates the theory within learning design. The article concludes with a discussion of how decision-making theory aligns with existing theories that are foundational to problem-solving, along with implications for future learning design.