© 2019 Elsevier Inc. Background: Thyroid-associated conditions are among the most common endocrine pathologies in the pediatric population, and their incidence has increased over the last several decades. Many of these conditions require surgical resection. We aimed to determine preoperative and intraoperative factors that affect unplanned postoperative readmission (UPOR)among pediatric patients undergoing thyroidectomy. Methods: Using the 2015 National Surgical Quality Improvement Program-Pediatric Public-Use-File (first year to include these procedures), pediatric thyroidectomy patients were collated. We evaluated demographics, comorbidities, perioperative variables, and postoperative morbidities, performing a multivariate analysis comparing individuals who required UPOR within 30 d of surgery to those who did not. Results: A total of 658 pediatric thyroidectomies were identified, of whom 2.6% required UPOR. Following multivariate analysis, male gender (P = 0.027), Black patients (P = 0.038), and preoperative inpatient status (P = 0.015)were associated with increased rates of UPOR. Patients with thyroiditis were significantly more likely to have UPOR (P = 0.023). Similarly, higher UPOR rates were seen in patients with a history of asthma (P = 0.030), cardiac comorbidities (P = 0.001), developmental delay (P = 0.047), and hematologic disorders (P = 0.021). In addition, patients operated by pediatric general surgeons had a lower rate of UPOR (1.3%)when compared with pediatric otolaryngology surgeons (4.3%; P = 0.019), as well as lower rates of surgical site infections (P = 0.041)and shorter operative times (P < 0.001). Conclusions: The number of children readmitted after thyroid surgery is low. Several factors, however, including underlying etiology of thyroid disease and surgeon subspecialty, highly determine the rate of UPOR after thyroid surgery in children.