Alfred Adler (February 7, 1870, Mariahilfer Straße 208, Rudolfsheim, Rudolfsheim-Fünfhaus – May 28, 1937) was an Austrian medical doctor, psychologist and founder of the school of individual psychology. In collaboration with Sigmund Freud and a small group of Freud's colleagues, Adler was among the co-founders of the psychoanalytic movement as a core member of the Vienna Psychoanalytic Society. He was the first major figure to break away from psychoanalysis to form an independent school of psychotherapy and personality theory. This was after Freud declared Adler's ideas as too contrary, leading to an ultimatum to all members of the Society (which Freud had shepherded) to drop Adler or be expelled, disavowing the right to dissent. Following this split, Adler would come to have an enormous, independent effect on the disciplines of counseling and psychotherapy as they developed over the course of the 20th century. He influenced notable figures in subsequent schools of psychotherapy such as Rollo May, Viktor Frankl, Abraham Maslow and Albert Ellis. His writings preceded, and were at times surprisingly consistent with, later neo-Freudian insights such as those evidenced in the works of Karen Horney, Harry Stack Sullivan and Erich Fromm.

Adler emphasized the importance of equality in preventing various forms of psychopathology, and espoused the development of social interest and democratic family structures for raising children. His most famous concept is the inferiority complex which speaks to the problem of self-esteem and its negative effects on human health (e.g. sometimes producing a paradoxical superiority striving). His emphasis on power dynamics is rooted in the philosophy of Nietzsche. Adler argued for holism, viewing the individual holistically rather than reductively, the latter being the dominant lens for viewing human psychology. Adler was also among the first in psychology to argue in favor of feminism making the case that power dynamics between men and women (and associations with masculinity and femininity) are crucial to understanding human psychology. Adler is considered, along with Freud and Jung, to be one of the three founding figures of depth psychology, which emphasizes the unconscious and psychodynamics.

Alfred Adler was the second child of seven children of a Hungarian-born, Jewish grain merchant and his wife. Early on, he developed rickets, which kept him from walking until he was four years old. He almost died of pneumonia when he was five and it was at this age that he decided to be a physician. Alfred was an active, popular child and an average student who was also known for his competitive attitude toward his older brother, Sigmund.

In 1895 he received a medical degree from the University of Vienna. During his college years, he became attached to a group of socialist students, among which he found his wife-to-be, Raissa Timofeyewna Epstein, an intellectual and social activist from Russia studying in Vienna. They married in 1897 and had four children, two of whom became psychiatrists.

He began his medical career as an ophthalmologist, but he soon switched to general practice, and established his office in a lower class part of Vienna, across from the Prater, a combination amusement park and circus. His clients included circus people, and it has been suggested that the unusual strengths and weaknesses of the performers led to his insights into "organ inferiorities" and "compensation".

In 1902 Adler received an invitation from Sigmund Freud to join an informal discussion group that included Rudolf Reitler and Wilhelm Stekel. They met regularly on Wednesday evenings at Freud's home, with membership expanding over time. This group was the beginning of the psychoanalytic movement (Mittwochsgesellschaft or the "Wednesday Society"). A long-serving member of the group, Adler became President of the Vienna Psychoanalytic Society eight years later (1910). He remained a member of the Society until 1911 when he and a group of supporters formally disengaged, the first of the great dissenters from Freudian psychoanalysis (preceding Carl Jung's notorious split in 1914). This departure suited both Freud and Adler since they had grown to dislike each other. During his association with Freud, Adler frequently maintained his own ideas which often diverged from Freud's. While Adler is often referred to as a "a pupil of Freud's", in fact this was never true; they were colleagues. In 1929 Adler showed a reporter with the New York Herald a copy of the faded postcard that Freud had sent him in 1902. He wanted to prove that he had never been a disciple of Freud's but rather that Freud had sought him out to share his ideas.

Adler founded the Society of Individual Psychology in 1912 after his break from the psychoanalytic movement. Adler's group initially included some orthodox Nietzschean adherents (who believed that Adler's ideas on power and inferiority were closer to Nietzsche than were Freud's). Their enmity aside, Adler retained a lifelong admiration of Freud's ideas on dreams and credited him for creating a scientific approach to their clinical utilization. Nevertheless, even with dream interpretation, Adler had his own theoretical and clinical approach. The primary differences between Adler and Freud centered on Adler's contention that the social realm (exteriority) is as important to psychology as is the internal realm (interiority). The dynamics of power and compensation extend beyond sexuality and the arena of gender and politics are important considerations that go beyond libido. Moreover, Freud did not share Adler's socialist beliefs. Trotsky's biography mentions his having discussions with Alfred Adler in Vienna.

Following Adler's break from Freud, he enjoyed considerable success and celebrity in building an independent school of psychotherapy and a unique Personality Theory. He traveled and lectured for a period of 25 years promoting his socially oriented approach. His intent was to build a movement that would rival, even supplant, others in psychology by arguing for the holistic integrity of psychological well-being with that of social equality. Adler's efforts were halted by World War I, during which he served as a doctor with the Austrian Army. After the conclusion of the war, his influence increased greatly. In the 1930s, he established a number of child guidance clinics. From 1921 onwards, he was a frequent lecturer in Europe and the United States, becoming a visiting professor at Columbia University in 1927. His clinical treatment methods for adults were aimed at uncovering the hidden purpose of symptoms using the therapeutic functions of insight and meaning.

Adler was concerned with the overcoming of the superiority/inferiority dynamic and was one of the first psychotherapists to discard the analytic couch in favor of two chairs. This allows the clinician and patient to sit together more or less as equals. Clinically, Adler's methods are not limited to treatment after-the-fact but extend to the realm of prevention by preempting future problems in the child. Prevention strategies include encouraging and promoting social interest, belonging, and a cultural shift within families and communities that leads to the eradication of pampering and neglect (especially corporal punishment). Adler's popularity was related to the comparative optimism and comprehensibility of his ideas. He often wrote for the lay public — unlike Freud and Jung, who tended to write almost exclusively for an academic audience. Adler always retained a pragmatic approach that was task-oriented. These "Life tasks" are occupation/work, society/friendship, and love/sexuality. Their success depends on cooperation. The tasks of life are not to be considered in isolation since, as Adler famously commented, "they all throw cross-lights on one another".

In his bestselling book, Man's Search for Meaning, Dr. Viktor E. Frankl compared his own "Third Viennese School of Psychotherapy" (after Freud's and Adler's schools) to Adler's analysis:

According to logotherapy, the striving to find a meaning in one's life is the primary motivational force in man. That is why I speak of a will to meaning in contrast to the "pleasure principle" (or, as we could also term it, the will to pleasure) on which Freudian psychoanalysis is centered, as well as in contrast to the will to power stressed by Adlerian psychology.