This review article considers some of the age-related changes in cognition that are likely to interact with hearing, listening effort, and cognitive energy. The focus of the review is on normative age-related changes in cognition; however, consideration is also given to older adults who experience clinically significant deficits in cognition, such as persons with Alzheimer's disease or who may be in a preclinical stage of dementia (mild cognitive impairment). The article distinguishes between the assessment of cognitive function for clinical versus research purposes. It reviews the goal of cognitive testing in older adults and discusses the challenges of validly assessing cognition in persons with sensory impairments. The article then discusses the goals of assessing specific cognitive functions (processing speed and attentional processes) for the purpose of understanding their relationships with listening effort. Finally, the article highlights certain concepts that are likely to be relevant to listening effort and cognitive energy, including some issues that have not yet received much attention in this context (e.g., conation, cognitive reserve, and second language speech processing).