It is unknown whether children with primary snoring and children with mild obstructive sleep apnea (OSA) represent populations with substantially different clinical characteristics. Nonetheless, an obstructive apnea-hypopnea index (AHI) of 1 or greater is often used to define OSA and plan for adenotonsillectomy (AT). To assess whether a combination of clinical characteristics differentiates children with primary snoring from children with mild OSA. Baseline data from the Pediatric Adenotonsillectomy Trial for Snoring (PATS) study, a multicenter, single-blind, randomized clinical trial conducted at 6 academic sleep centers from June 2016 to January 2021, were analyzed. Children aged 3.0 to 12.9 years with polysomnography-diagnosed (AHI <3) mild obstructive sleep-disordered breathing who were considered candidates for AT were included. Data analysis was performed from July 2022 to October 2023. Logistic regression models were fitted to identify which demographic, clinical, and caregiver reports distinguished children with primary snoring (AHI <1; 311 patients [67.8%]) from children with mild OSA (AHI 1-3; 148 patients [32.2%]). A total of 459 children were included. The median (IQR) age was 6.0 (4.0-7.5) years, 230 (50.1%) were female, and 88 (19.2%) had obesity. A total of 121 (26.4%) were Black, 75 (16.4%) were Hispanic, 236 (51.5%) were White, and 26 (5.7%) were other race and ethnicity. Black race (odds ratio [OR], 2.08; 95% CI, 1.32-3.30), obesity (OR, 1.80; 95% CI, 1.12-2.91), and high urinary cotinine levels (>5 µg/L) (OR, 1.88; 95% CI, 1.15-3.06) were associated with greater odds of mild OSA rather than primary snoring. Other demographic characteristics, clinical examination findings, and questionnaire reports did not distinguish between primary snoring and mild OSA. A weighted combination of the statistically significant clinical predictors had limited ability to differentiate children with mild OSA from children with primary snoring. In this analysis of baseline data from the PATS randomized clinical trial, primary snoring and mild OSA were difficult to distinguish without polysomnography. Mild OSA vs snoring alone did not identify a clinical group of children who may stand to benefit from AT for obstructive sleep-disordered breathing. ClinicalTrials.gov Identifier: NCT02562040.