Mothers of children with cancer experience significant distress associated with their children's diagnosis and treatment. The efficacy of problem-solving skills training (PSST), a cognitive-behavioral intervention based on problem-solving therapy, was assessed among 430 English- and Spanish-speaking mothers of recently diagnosed patients. Participants were randomized to usual psychosocial care (UPC; n = 213) or UPC plus 8 sessions of PSST (PSST; n = 217). Compared with UPC mothers, PSST mothers reported significantly enhanced problem-solving skills and significantly decreased negative affectivity. Although effects were largest immediately after PSST, several differences in problem-solving skills and distress levels persisted to the 3-month follow-up. In general, efficacy for Spanish-speaking mothers exceeded that for English-speaking mothers. Findings also suggest young, single mothers profit most from PSST.