Background Different criteria for diagnosing posttraumatic stress disorder (PTSD) have been recommended by the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM‐5) and the proposed 11th edition of the International Classification of Diseases (ICD‐11). Although children are vulnerable to PTSD following disasters, little is known about whether these revised criteria are appropriate for preadolescents, as diagnostic revisions have been based primarily on adult research. This study investigated rates of PTSD using DSM‐IV, DSM‐5, and ICD‐11 diagnostic criteria, and their associations with symptom severity, impairment, and PTSD risk factors. Methods Children (7–11 years) exposed to Hurricanes Ike (n = 327) or Charley (n = 383) completed measures 8–9 months postdisaster. Using diagnostic algorithms for DSM‐IV, DSM‐5, and ICD‐11, rates of ‘probable’ PTSD were calculated. Results Across samples, rates of PTSD were similar. However, there was low agreement across the diagnostic systems, with about a third overlap in identified cases. Children identified only by ICD‐11 had higher ‘core’ symptom severity but lower impairment than children identified only by DSM‐IV or DSM‐5. ICD‐11 was associated with more established risk factors for PTSD than was DSM‐5. Conclusions Findings revealed differences in PTSD diagnosis across major diagnostic systems for preadolescent children, with no clear advantage to any one system. Further research on developmentally sensitive PTSD criteria for preadolescent children is needed.