A psychologist is a professional who practices psychology and studies mental states, perceptual, cognitive, emotional, and social processes and behavior.

Unlike psychiatric physicians and psychiatric nurse-practitioners, psychologists usually cannot prescribe medication, but depending on the jurisdiction, some psychologists with additional training can be licensed to prescribe medications; qualification requirements may be different from a bachelor's degree and master's degree.

[3] Psychologists can work with a range of institutions and people, such as schools, prisons, in a private clinic, in a workplace, or with a sports team.

The standard route to full membership (MAPS) of the APS usually requires four years of APAC-accredited undergraduate study, plus a master's or doctorate in psychology from an accredited institution.

An alternate route is available for academics and practitioners who have gained appropriate experience and made a substantial contribution to the field of psychology.

[18] A professional in the U.S. or Canada must hold a graduate degree in psychology (MA, Psy.D., Ed.D., or Ph.D.), or have a provincial license to use the title "psychologist".

The restriction for psychologists (licensed professionals) is governed by National Supervisory Authority for Welfare and Health (Finland) (Valvira).

The psychotherapeutic training combines in-depth theoretical knowledge with supervised patient care and self-reflection units.

[24] After many years of inter-professional political controversy, non-physician psychotherapy was given an adequate legal foundation through the creation of two new academic healthcare professions.

It can only be used by people who hold a relevant license or certificate, which is issued by the Greek authorities, to practice as a psychologist.

[27] Psychologists in Greece are not required to register with any psychology body in the country in order to legally practice the profession.

[35] This is to protect the public by providing assurance that the title-holder is registered and therefore qualified and competent to practice, and can be held accountable.

In Norway, the title "psychologist" is restricted by law and can only be obtained by completing a six-year integrated program, leading to the Candidate of Psychology degree.

[36] In South Africa,[37] psychologists are qualified in either clinical, counseling, educational, organizational, or research psychology.

[39] Registration with the Health Professions Council of South Africa (HPCSA)[40] is required and includes a Continuing Professional Development component.

The master's program consists of seminars, coursework-based theoretical and practical training, and a dissertation of limited scope, and is (in most cases) two years in duration.

[c] The minimal requirement for full membership can be waived in circumstances where there is evidence that significant contribution or performance in the field of psychology has been made.

Some psychology specialties, such as clinical neuropsychology, require a 2-year postdoctoral experience regardless of the state, as set forth in the Houston Conference Guidelines.

Today in America, about half of all clinical psychology graduate students are being trained in PhD programs that emphasize melding research with practice and are conducted by universities—with the other half in PsyD programs, which less focus on research (similar to professional degrees for medicine and law).

[53] Both types of doctoral programs (PhD and PsyD) envision practicing clinical psychology in a research-based, scientifically valid manner, and most are accredited by the APA.

The PsyD program prepares the student primarily as a practitioner for clinical practice (e.g., testing, psychotherapy), but also as a scholar that consumes research.

[65] [66] Clinical psychologists can offer a range of professional services, including:[67] In practice, clinical psychologists might work with individuals, couples, families, or groups in a variety of settings, including private practices, hospitals, community mental health centers, schools, businesses, and non-profit agencies.

Legislation in Idaho, Iowa, Louisiana, New Mexico, Illinois, and Colorado has granted those who complete an additional master's degree program in clinical psychopharmacology authority to prescribe medications for mental and emotional disorders.

To practice with the title of "psychologist", in almost all cases a doctoral degree is required (PhD, PsyD, or EdD in the U.S.).

Normally, after the degree, the practitioner must fulfill a certain number of supervised postdoctoral hours ranging from 1,500 to 3,000 (usually taking one to two years), and pass the EPPP and any other state or provincial exams.

[74] By and large, a professional in the U.S. must hold a doctoral degree in psychology (PsyD, EdD, or PhD), and/or have a state license to use the title psychologist.

Although clinical psychologists and psychiatrists share the same fundamental aim—the alleviation of mental distress—their training, outlook, and methodologies are often different.

In five U.S. states (New Mexico, Louisiana, Illinois, Iowa, Idaho, and Colorado), psychologists with clinical psychopharmacology training have been granted prescriptive authority for mental health disorders.

While this training is available for physicians via dual MD/PhD programs, it is not typically included in standard medical education, although psychiatrists may develop research skills during their residency or a psychiatry fellowship (post-residency).

Psychiatrists, as licensed physicians, have been trained more intensively in other areas, such as internal medicine and neurology, and may bring this knowledge to bear in identifying and treating medical or neurological conditions that present with primarily psychological symptoms such as depression, anxiety, or paranoia (e.g., hypothyroidism presenting with depressive symptoms, or pulmonary embolism with significant apprehension and anxiety).