Educational psychology is the branch of psychology concerned with the scientific study of human learning. The study of learning processes, from both cognitive and behavioral perspectives, allows researchers to understand individual differences in intelligence, cognitive development, affect, motivation, self-regulation, and self-concept, as well as their role in learning. The field of educational psychology relies heavily on quantitative methods, including testing and measurement, to enhance educational activities related to instructional design, classroom management, and assessment, which serve to facilitate learning processes in various educational settings across the lifespan.

Educational psychology can in part be understood through its relationship with other disciplines. It is informed primarily by psychology, bearing a relationship to that discipline analogous to the relationship between medicine and biology. It is also informed by neuroscience. Educational psychology in turn informs a wide range of specialties within educational studies, including instructional design, educational technology, curriculum development, organizational learning, special education, classroom management, and student motivation. Educational psychology both draws from and contributes to cognitive science and the learning theory. In universities, departments of educational psychology are usually housed within faculties of education, possibly accounting for the lack of representation of educational psychology content in introductory psychology textbooks.

The field of educational psychology involves the study of memory, conceptual processes, and individual differences (via cognitive psychology) in conceptualizing new strategies for learning processes in humans. Educational psychology has been built upon theories of operant conditioning, functionalism, structuralism, constructivism, humanistic psychology, Gestalt psychology, and information processing.

Educational psychology has seen rapid growth and development as a profession in the last twenty years. School psychology began with the concept of intelligence testing leading to provisions for special education students, who could not follow the regular classroom curriculum in the early part of the 20th century. Another main focus of school psychology was to help close the gap for children of colour, as the fight against racial inequality and segregation was still very prominent, during the early to mid-1900s. However, "school psychology" itself has built a fairly new profession based upon the practices and theories of several psychologists among many different fields. Educational psychologists are working side by side with psychiatrists, social workers, teachers, speech and language therapists, and counselors in an attempt to understand the questions being raised when combining behavioral, cognitive, and social psychology in the classroom setting.

As a field of study, educational psychology is fairly new and was not considered a specific practice until the 20th century. Reflections on everyday teaching and learning allowed some individuals throughout history to elaborate on developmental differences in cognition, the nature of instruction, and the transfer of knowledge and learning. These topics are important to education and, as a result, they are important in understanding human cognition, learning, and social perception.

Some of the ideas and issues pertaining to educational psychology date back to the time of Plato and Aristotle. Philosophers as well as sophists discussed the purpose of education, training of the body and the cultivation of psycho-motor skills, the formation of good character, the possibilities and limits of moral education. Some other educational topics they spoke about were the effects of music, poetry, and the other arts on the development of the individual, role of the teacher, and the relations between teacher and student. Plato saw knowledge acquisition as an innate ability, which evolves through experience and understanding of the world. This conception of human cognition has evolved into a continuing argument of nature vs. nurture in understanding conditioning and learning today. Aristotle, on the other hand, ascribed to the idea of knowledge by association or schema. His four laws of association included succession, contiguity, similarity, and contrast. His studies examined recall and facilitated learning processes.

John Locke is considered one of the most influential philosophers in post-renaissance Europe, a time period that began around the mid-1600s. Locke is considered the "Father of English Psychology". One of Locke's most important works was written in 1690, named An Essay Concerning Human Understanding. In this essay, he introduced the term "tabula rasa" meaning "blank slate." Locke explained that learning was attained through experience only and that we are all born without knowledge.

He followed by contrasting Plato's theory of innate learning processes. Locke believed the mind was formed by experiences, not innate ideas. Locke introduced this idea as "empiricism", or the understanding that knowledge is only built on knowledge and experience.