Neuroscience research that explains how the brain learns is a dynamic field. Since the 1990s, there has been explosive growth in information about the neurophysiology of learning. A discussion of the neuroanatomy that is necessary to understand this research is presented first. Following the discussion of anatomy and physiology, current brain research is described, with particular focus on its implications for teaching adult students in an online environment. In addition, two instructional design theories (Gardner’s multiple intelligence and Kovalik’s integrated thematic instruction) that have a basis in neuroscience are examined. Recommendations founded on brain-based research, with a focus on adult education, follow, including specific activities such as crossed-lateral movement patterns and detailed online activities that can be incorporated into an online learning environment or a distance learning class (and face-to-face classroom) for adults. Comprehensive recommendations and guidelines for online learning design have been provided as suggestions for making maximum use of the brain-based principles discussed in this chapter.