BACKGROUND:The way families negotiate diagnosis and early treatment for pediatric cancer sets the stage for their adaptation throughout treatment and survivorship. The Psychosocial Assessment Tool (PAT) is a brief parent‐report screener capable of systematically identifying families at risk for problems of adaptation. The current study evaluated stability and predictive validity of PAT psychosocial risk classification with regard to distress, family functioning, and the use of psychosocial services over the first 4 months of treatment.METHODS:Caregivers of children with cancer completed the PAT and measures of distress and family functioning at diagnosis and again 4 months into treatment. At the second time point, social workers completed checklists of services provided and rated the intensity of their work with each family. Referrals to psychologists also were tracked.RESULTS:Psychosocial risk classification, based on the PAT, was stable across the first 4 months of cancer treatment; 57% to 69% of families remained at the same level of risk. PAT total scores did not differ across time, but subscale scores indicated increases in family and child (patient) problems and decreases in unhelpful beliefs. Families classified at higher levels of psychosocial risk at diagnosis had more distress, more family problems, and greater psychosocial service use 4 months into treatment.CONCLUSIONS:Understanding and identifying risks for psychosocial adjustment difficulties within families of children with cancer, considering changes across treatment and beyond, is very complex. Despite evidence of the predictive validity of PAT, additional research is necessary to find ways to effectively use this screener in practice to guide intervention. Cancer 2009;115(18 suppl):4339–49. © 2009 American Cancer Society.