Mental Health assessments can be conducted on children, adolescents or adults. The purpose is to identify psychological and environmental factors that may be causing emotional, behavioral or interpersonal difficulties. When appropriate, a diagnosis is given based on the symptoms that have been identified. Options for intervention and treatment are also provided in a written report which includes all of the relevant information that has been gathered. It is important for the psychologist completing the assessment to have a thorough understanding of mental health conditions and how they are expressed.

With respect to children and adolescents, the focus is often on the behavioral manifestations of emotional disturbance or emerging mental health issues. Information is gathered by conducting a clinical interview with the child or adolescent, interviewing parents or teachers as appropriate, and having any number of behavior rating scales and inventories completed by these same individuals. It is sometimes necessary to proceed with a psychoeducational assessment (intellectual and academic testing) to examine the possibility that the behaviors in question may be related to an underlying learning disorder that is causing frustration and irritability.

Mental Health assessments on adults also include a clinical interview to obtain relevant information about each of the following areas: family of origin, childhood experiences, educational background, employment history, medical history, and a review of psychological, social and interpersonal factors. The client is also asked to fill out one or more self-report inventories that evaluate various aspects of personality as well as emotional, behavioral and interpersonal characteristics. In certain circumstances the client may be asked for permission to obtain additional information and insight from significant others (e.g., parents, spouses, siblings or friends).