Nursing home social work services are integral to resident interdisciplinary care planning and treatments to meet residents' psychosocial needs. Data from the Online Survey Certification and Reporting database examine the relationship among numbers of qualified social workers, social service staff, and deficiency citation scores for resident assessment violations in 16,511 United States nursing homes in 2007. Using a generalized estimating equation, we show a relationship between numbers of qualified social workers, social service staff, and facilities' resident assessment-related deficiency scores. Having more qualified social workers and more social service staff is related to lower assessment deficiency scores supporting the important role of social workers and social services in nursing homes. Implications for evidence-based practice and policy are discussed.KEYWORDS deficiency citation score, nursing home, quality of care, resident assessment, social work staff As members of the clinical team in nursing homes (NHs), social work staff (qualified social workers and social service staff) play a vital role in the development and functioning of NH care plans. Social work is a profession that aims to assist people in resolving issues and in successfully coping with problems in their everyday lives. Social workers also identify and connect people with needed services and advocate for people who may not be able to do so for themselves. Social workers are often the staff in NHs who deal