Dietary therapies based on exclusion of usual dietary elements induce remission in children with Crohn's disease (CD), whereas re-exposure induces rebound inflammation. We investigated whether a short trial of dietary therapy, to identify patients with and without a rapid response or remission on the diet (DiRe), can be used to predict success or failure of long-term dietary therapy. We collected data from the multicenter randomized trial of the CD exclusion diet (CDED). We analyzed data from 73 children with mild to moderate CD (mean age, 14.2 ± 2.7 y) randomly assigned to groups given either exclusive enteral nutrition (EEN, n = 34) or the CDED with 50% (partial) enteral nutrition (n = 39). Patients were examined at baseline and at weeks 3 and 6 of the diet. Remission was defined as CD activity index scores below 10 and response was defined as a decrease in score of 12.5 points or clinical remission. Inflammation was assessed by measurement of C-reactive protein. At week 3 of the diet, 82% of patients in the CDED group and 85% of patients in the EEN group had a DiRe. Median serum levels of C-reactive protein had decreased from 24 mg/L at baseline to 5.0 mg/L at week 3 (P < .001). Among the 49 patients in remission at week 6, 46 patients (94%) had a DiRe and 81% were in clinical remission by week 3. In multivariable analysis, remission at week 3 increased odds of remission by week 6 (odds ratio, 6.37; 95% CI, 1.6-25; P = .008) whereas poor compliance reduced odds of remission at week 6 (odds ratio, 0.75; 95% CI, 0.012-0.46; P = .006). For pediatric patients with active CD, dietary therapies (CDED and EEN) induce a rapid clinical response (by week 3). Identification of patients with and without a rapid response to diet might help identify those who, with compliance, will be in clinical remission by week 6 of the diet. ClinicalTrials.gov no: NCT01728870. Copyright © 2021 AGA Institute. Published by Elsevier Inc. All rights reserved.