Objective: The current study examined the roles of constructive and dysfunctional problem-solving strategies in the relationships between illness uncertainty and adjustment outcomes (i.e., anxious, depressive, and posttraumatic stress symptoms) in caregivers of children newly diagnosed with cancer. Methods: Two hundred thirty-eight caregivers of children (0-19 years of age) newly diagnosed with cancer (2-14 weeks since diagnosis) completed measures of illness uncertainty, problem-solving strategies, and symptoms of anxiety, depression, and posttraumatic stress. Results: A mediation model path analysis assessed constructive and dysfunctional problem-solving strategies as mediators between illness uncertainty and caregiver anxious, depressive, and posttraumatic stress symptoms. Dysfunctional problem-solving scores partially mediated the relationships between illness uncertainty and anxious, depressive, and posttraumatic stress symptoms. Constructive problem-solving scores did not mediate these relationships. Conclusions: The current findings suggest that illness uncertainty and dysfunctional problem-solving strategies, but not constructive problem-solving strategies, may play a key role in the adjustment of caregivers of children newly diagnosed with cancer. Interventions aimed at managing illness uncertainty and mitigating the impact of dysfunctional problem-solving strategies may promote psychological adjustment.