NASMHPD has formal affiliations with the National Association of Consumer/Survivor Mental Health Administrators (NAC/SMHA), an organization that represents the Directors of the Offices of Consumer Affairs within state mental health agencies; the National Coalition on Mental Health and Deaf Individuals (NCMHDI), a non-profit corporation established in 2008 to provide leadership and support in the areas of public mental health and deaf and hard of hearing populations in the United States; and with the Multi-State Behavioral Health Consortium, a nationwide collaboration between State Mental Health Agencies to foster dialogue and cooperation in the area of disaster and mental health services.

In its early days, NASMHPD maintained a research division that was reconstituted in 1987 as the NASMHPD Research Institute, Inc. (NRI), a separate non-profit organization. The mission of the NRI is to promote quality and accountability of mental health services by generating and facilitating the use of relevant research, data, and information that meets the collective and individual needs of state mental health agencies.

In addition, NASMHPD has an affiliation with the approximately 220 state psychiatric hospitals, which include hospitals for children, adults, older persons, and people who have entered the mental health system via the court system. NASMHPD holds a National Summit every two years to convene the superintendents of all of these hospitals. The superintendents have established the following four regional organizations, each of which meet annually: the Southern States Psychiatric Hospital Association (SSPHO), the Midwestern Association of Mental Health Organizations (MASMHO), the Western Psychiatric State Hospital Association (WPSHA), and the Northeast Region.

NASMHPD members play a vital role in the delivery, financing, and evaluation of mental health services within a rapidly evolving healthcare environment. The principal programs operated, funded, and/or regulated by NASMHPD members serve people who have serious mental illnesses, developmental disabilities, and/or substance use disorders. This role impacts many other constituencies as well. In recognition of these mutual interests, NASMHPD has effectively responded to and collaborated with other organizations and individuals including those representing consumers, families, and state mental health planning and advisory councils.

As a private, not-for-profit 501(c)(3) membership organization, NASMHPD helps set the agenda and determine the direction of state mental health agency interests across the country, historically including state mental health planning, service delivery, and evaluation. The association provides members with the opportunity to exchange diverse views and experiences, learning from one another in areas vital to effective public policy development and implementation. NASMHPD provides a broad array of services designed to identify and respond to critical policy issues, cutting-edge consultation, training, and technical assistance, and together with the NASMHPD Research Institute, Inc., a partner organization, apprises constituents of the latest in mental health research in administration and services delivery. Some of the areas in which NASMHPD staff combine their expertise with members and other key constituents include: advancing intergovernmental cooperation; promoting efficient and effective management strategies; supporting state, local, and jurisdictional relationships and activities; providing policy analysis and development, technical assistance, and training in critical areas of policy and practice; responding effectively to changing organizational, practice, and finance trends; and identifying and sharing models of excellence on a myriad of topics and issues.