To better understand the process and rationale of lifelong learning, one should have rudimentary information about learning theories and models. Learning theories provide frameworks that help educators and researchers understand how individuals acquire, retain, and apply knowledge. This chapter reviews several prominent learning theories—behaviorism, cognitivism, connectivism, constructivism, and chaos complexity theory—highlighting their core principles, instructional implications, and relevance in contemporary educational practices. A meaningful understanding of these theories and models depends on basic knowledge of the underlying philosophical and epistemological tenets of learning theories. Hence, this chapter first presents the broad schools of philosophy along with their sub-classifications. It then puts forward a brief overview of the major epistemologies. The chapter proceeds with introducing broad learning theories. More comprehensive information and elaborations on each paradigm are then presented. To do so, different schools of behaviorism, nativism, cognitivism (information processing, processability, operating principles), connectionism, emergentism, individual constructivism, social constructivism, and chaos complexity theory are introduced.