- American Psychiatric Association
- American Psychological Association (APA)
- American Psychological Society (APS)
- Americans With Disabilities Act (ADA)
- Ames Room
- Amnesia
- Anger
- Animal Experimentation
- Anna Freud
- Anne Anastasi
- Anorexia
- Antidepressants
- Antisocial Behavior
- Antisocial Personality Disorder
- Anxiety/Anxiety Disorders
- Apgar Score
- Aphasia
- Applied Psychology
- Archetype
- Arnold Allan Lazarus
- Arnold Gesell
- Art Therapy
- Arthur Otis
- Arthur R. Jensen
- Artificial Intelligence
- Assessment, Psychological
- Assimilation
- Associationism
- Attachment
- Attention
