Mary Hayden Wilson BSW,

A psychologist is an individual who is licensed to practice psychology which is defined as the observation, description, evaluation, interpretation, and modification of human behavior by the application of psychological principles, methods, and procedures, for the purpose of preventing or eliminating symptomatic, maladaptive, or undesired behavior and of enhancing interpersonal relationships, work and life adjustment, personal effectiveness, behavioral health, and mental health. The practice of psychology includes, but is not limited to, psychological testing and the evaluation or assessment of personal characteristics, such as intelligence, personality, abilities, interests, aptitudes, and neuropsychological functioning; counseling, psychoanalysis, psychotherapy, hypnosis, biofeedback, and behavior analysis and therapy; diagnosis and treatment of mental and emotional disorder or disability, alcoholism and substance abuse, disorders of habit or conduct, as well as of the psychological aspects of physical illness, accident, injury, or disability; and psycheducational evaluation, therapy, remediation, and consultation. Psychological services may be rendered to individuals, families, groups and the public.

An individual trained and educated in a systematic process of assisting persons with physical, mental, developmental, cognitive, and emotional disabilities to achieve their personal, career, and independent living goals assessment and appraisal, diagnosis and treatment planning, career (vocational) counseling, individual and group counseling interventions for adjustments to the medical and psychosocial impact of disability, case management, program evaluation and research, job analysis and placement counseling, and consultation on rehabilitation resources and technology. Certification generally requires a Master's degree with specialized courses in rehabilitation processes and technology.

Source: NUCC, CMS