BACKGROUND: Increases in demands on patients' family members that are not reduced by family strengths may contribute to decreases in family adaptation and complicate patients' recovery after trauma. The purpose of this study was to examine family demands (prior stressors and severity of patients' injuries) and family strengths and capabilities (hardiness, resources, coping, and problem-solving communication) associated with outcomes of family well-being and adaptation. METHODS: A multivariate, descriptive design based on the Resiliency Model of Family Stress was used. A convenience sample of family members (N = 51) of adult patients participated within the first 2 days of critical injury. Family demands were measured with the Family Inventory of Life Events and Changes and the Acute Physiology, Age, and Chronic Health Evaluation III. Family strengths were measured with the Family Hardiness Index, Family Inventory of Resources for Management, Family Crisis Oriented Personal Evaluation Scale, and Family Problem Solving Communication Index. Family adaptation outcomes were measured with the Family Well Being Index and Family Adaptation Scale. RESULTS: Increases in family demands were significantly related to decreases in family strengths and family adaptation. Family demands scores accounted for 40% of the variance in family well-being scores. The only significant family strength variable influencing family adaptation was problem-solving communication. CONCLUSIONS: Increases in family demands seem to be an important indicator of the amount of assistance a family may need. Interventions that help mobilize family strengths, such as problem-solving communication, may be effective in promoting the adaptation of families of critically injured patients.