['To determine the relationship of both pubertal development and sex to childhood irritable bowel syndrome (IBS) clinical characteristics including gastrointestinal symptoms (eg, abdominal pain) and psychological factors.', 'Cross-sectional study with children ages 7-17 years (n\u2009=\u2009143) with a pediatric Rome III IBS diagnosis recruited from both primary and tertiary clinics between January 2009 and January 2014. Subjects completed 14-day prospective pain and stool diaries, as well as validated questionnaires assessing several psychological factors (somatization, depression, anxiety) and Tanner stage. Stool form ratings were completed using the Bristol Stool Form Scale.', 'Girls with higher Tanner scores (more mature pubertal development) had both decreased pain severity and pain interference; in contrast, boys with higher Tanner scores had both increasing pain severity (β\u2009=\u20090.40, P\u2009=\u2009.02) and pain interference (β\u2009=\u20090.16, P\u2009=\u2009.02). Girls (vs boys), irrespective of pubertal status, had both increased somatic complaints (P\u2009=\u2009.005) and a higher percentage (P\u2009=\u2009.01) of hard (Bristol Stool Form Scale type 1 or 2) stools. Pubertal status and sex did not significantly relate to IBS subtype, pain frequency, stooling frequency, anxiety, or depression.'] Do childhood Irritable Bowel Syndrome Characteristics Are Related to Both Sex and Pubertal Development?