Objective To develop and validate a Distress Thermometer for Parents (DT-P) for chronically ill children and to determine a cutoff score for clinical distress. Study design Parents of a chronically ill child (0-18 years) were recruited via announcements or were actively approached at the outpatient clinics of the Emma Children's Hospital/Academic Medical Center and Vrije Universiteit Medical Center. We modeled the development of the DT-P on the Distress Thermometer used in oncology medical care. The DT-P consists of a thermometer score from 0 (no distress) to 10 (extreme distress) and a problem list (practical, social, emotional, physical, cognitive, and parenting domains). The DT-P was validated with the Hospital Anxiety and Depression Scale (HADS) and the Parenting Stress Index. Results The mean thermometer score of the 706 participating parents was 3.7 (SD 3.0). The thermometer score and the scores in the practical, emotional, physical, and cognitive problem domains were strongly related to anxiety, depression, and the total score of the HADS (0.55 ≤ r ≤ 0.72). The thermometer score and all problem domain scores were moderately-to-strongly related to the Parenting Stress Index (0.38 ≤ r ≤ 0.63). A cutoff-score of 4 correctly identified 86% of “clinical HADS cases” (sensitivity) and 67% of “nonclinical HADS cases” (specificity). Conclusions We developed the DT-P and examined its diagnostic utility in a large sample. The DT-P appeared to be a valid and useful short screening-tool for identifying parental distress.