To determine the incidence of and identify predictive factors for thyroid bed recurrence (TBR) or lymph node recurrence (NR), we performed a chart review and retrospective multivariate Cox regression analysis on 235 patients with DTC diagnosed at age #18 y and managed with curative intent at our tertiary referral center from 1973 to 2002; 40 of these patients had distant metastases at diagnosis. We also determined overall and recurrence–free survival and generated curves for these variables using Kaplan–Meier and Cox univariate analysis. We sought to assess whether extensive surgical treatment, post surgical radioiodine therapy, or both decrease the risk of locoregional recurrence (LR) after curative primary treatment in children and adolescents diagnosed with differentiated thyroid cancer (DTC) at age #18 y. During a median follow–up of 82 mo (range, 5–402 mo), no DTC–related deaths occurred, 203 (86%) children remained recurrence–free, and 32 (14%) children had LR, including TBR in 9 (28% of LR), NR in 20 (63% of LR), and both in 3 (9% of LR). Among patients treated with radical intent and showing no distant metastases, the most recent thyroglobulin  level was ,1 ng/mL in all but 4% of cases. The median time from the first surgery to LR was 37 mo (range, 9–280 mo). In multivariate analysis, significant risk factors for TBR were less than total thyroidectomy and lack of postsurgical radioiodine treatment (respective risk increases of 9.5 [P 5 0.04] and 11 times [P 5 0.03]). For NR, classic papillary histology, incomplete primary lymph node management (i.e., lack of modified lymphadenectomy of affected lymph nodes or lack of confirmation ofdisease–free nodes by intraoperative staging), and absence of adjuvant radioiodine therapy were independent significant predictive factors that increased the recurrence risk by 1.9 (P 5 0.02), 3.3 (P 5 0.02), and 3.2 (P 5 0.02) times, respectively. Age or sex did not correlate with LR risk. In DTC patients#18 y of age, extensive initial therapy—consisting of total thyroidectomy combined with modified lymphadenectomy.