Psychological assessment has been at the core of applied psychology; and historically, applied psychologists often did little more than assessment. However, with increased specialization, those who provide assessment services has become limited. Today, most states and provinces have governing boards which limit the provision of psychological assessment services to licensed practitioners, the breadth of services they can provided limited by the level of training. Generally, academic psychologists (i.e., those who are not licensed clinicians) cannot provide assessment services outside of purely research purposes. Individuals often sub-specialize even within assessment:

Clinical Psychologists are those individuals who provide diagnostic and treatment oriented evaluations, often at the request of other therapists or patients. They are often the broadest range of assessment services and function if various settings, ranging from private practice offices to major medical hospitals.

Forensic Psychologists are more limited in the types of evaluations performed and settings in which services are rendered. Often called upon by courts and/or attorneys, forensic psychologists evaluate individuals for very specific purposes, such as competency to stand trial, mental status at time of offense (for insanity pleas) in criminal cases custody evaluations for family courts, and disability evaluations for administrative hearings to name just a few. Due to the complex nature of forensic evaluations, these psychologists often receive advanced training in forensic evaluation.

School Psychologists vary in the degree of training and the nature of the evaluations performed. Some have doctorate level degrees (Ph.D. or Ed.D) and provide a broad range of services equivalent to clinical psychologists, whereas others are trained at the master's level and are limited to the provision of educational and intellectual assessment. Limitations in breadth are accounted for by the depth of training received in their area of expertise. As the name implies, these psychologists are often function in public and private school settings.

Industrial/Organizational Psychologists provided services to industry, business, and various public and private organizations. In regards to assessment, these services often focus on pre-employment screenings and job-performance evaluations. Generally doctorate level psychologists, the types of evaluations are limited only by the nature of the setting.

PhD's and PsyD's: Traditionally, doctorate level psychologists have been awarded PhD's (Doctorate in Philosophy), reflecting the academic nature of the profession. However, with increasing number of psychologists pursuing applied degrees, institutions began awarding the PsyD degree (Doctorate in Psychology). The major difference between the two degrees relates to the type and level of training. PhD psychologists have a greater emphasis on research, whereas PsyD psychologists often focus on application; Depending upon the training institution, PsyD's may also complete programs earlier than PhD psychologists because of less rigorous publication and research demands. As to which degree is better suited at providing psychological services, there is currently little to support either declaring superiority and any discussions toward this issue often result in little more than insulting diatribes and self-serving criticisms of each other. For practical purposes, both degrees are recognized throughout the world and psychologists with either degree can be licensed and have identical professional privileges.